If you need to slash existing debt costs, borrow for something new (don't mention Xmas yet) or make a quick buck, there's a host of new scorching deals that make credit cards a hot option. Used well, they're a great tool. Used badly, you'll get burnt - so never borrow unnecessarily. Our pick of the bunch is below, but first...

1. Always check if you'll be accepted for top deals via our bolstered eligibility calc. Normally, the only way to find out is to apply, yet too many applications hurt your credit score. Our Credit Card Eligibility Calc does a soft search, so while you see it on your file, lenders can't act upon it, protecting your creditworthiness.

It shows your odds from 0% to 95% of getting top deals. We had most card providers in there already, but a big one which was missing, Tesco Bank, is now in.

Pre-approval goes a step further and tells you if you've a 100% acceptance chance, subject to ID and fraud checks. You could do it with Aqua, MBNA and Virgin cards, and from this week, many Barclaycards too.

2. New. Free £25 M&S vch for spending a penny via 25mth 0% spending card. Accepted new M&S Bank card holders (eligibility calc / apply*) who apply via our specific link and spend anything, even just 1p, before 31 Oct get a £25 M&S voucher to use on food, clothing, homewares, wine, flowers & more, as long as you've not held its credit card in the past year. Plus it's 25mths 0% on spending (18.9% rep APR after). You can get 27mths 0% elsewhere - the longest-ever 0% spending period - but even though M&S is a tad shorter, combined with the freebie, it's a corker.

- Extra £5 of points. The first time you use it (on most things) at M&S you get 500 M&S points, worth £5. So buy a Tesco banana and you get £25, buy an M&S banana and it's £30. You can pay it off and forget it or keep using for 1pt per £1 spent in M&S and per £5 elsewhere.

Need a longer 0%? FULL help and all the best buys in 0% Spending Cards (APR Examples) - here are the table-toppers by length:

- Sainsbury's (eligibility calc / apply*) 27mths 0% (18.9% rep APR after).
- Post Office (eligibility calc / apply*) 27mths 0%, though if you fail to spend in first 3mths it's 16mths 0% (18.9% rep APR after).

0% spending card GOLDEN RULES:
a) Pay at least the monthly min & always stick to the credit limit or you can lose the 0%.
b) Plan to clear debt before the 0% ends (or do a balance transfer), or the rate jumps to the rep APR.
c) These cards are usually ONLY cheap for spending - avoid balance transfers and cash withdrawals.

3. New. Longest-EVER no-fee 0% balance transfer card. If you're paying credit card interest... STOP. Shift debt to a 0% balance transfer card to pay NO interest. These pay off existing credit and store cards, so you owe them instead, but at 0% (though you usually can't transfer a balance from a card issued by the same lender).

As Kelly told us: "Used the eligibility calc, got 35mths 0% and shifted £11,000 from 29.9%. Shocked by the savings." That's a saving of £4,900 if it's cleared within the 35mths.

There's been a host of new launches this week - Halifax yesterday was the standout with a longest-ever NO-FEE balance transfer: up to 25mths 0%. Follow our mantra though of going for the lowest fee in the time you're sure you can repay. See Best Balance Transfers for the top deals - here's the pick.

Card 0% length (APR AFTER 0% ENDS) TRANSFER FEE (1)

New. Halifax (eligibility calc / apply*) - joint-longest 0%, but 'up to' 41mths

Up to 41mths 0% (18.9%) 3.5%

Virgin (eligibility calc / apply*) - joint-longest 0% + pre-approval check

41mths 0% (20.9%) 4% (min £3)

New. Lloyds (eligibility calc / apply*) - long 0% but 'up to' 40mths

Up to 40mths 0% (18.9%) 2.41%

Sainsbury's (eligibility calc / apply*) - long 0%, special fee for Nectar holders

40mths 0% (18.9%) 2.42% (min £3)

New. Barclaycard (eligibility calc / apply*) - long 0% with low fee + pre-approval

Up to 32mths 0% (18.9%) 0.68%

New. Halifax (eligibility calc / apply*) - Longest NO-FEE 0% but 'up to' 25mths

Up to 25mths 0% (18.9%) None

Tesco (eligibility calc / apply*) - next longest NO-FEE 0%

24mths 0% (20.6%) None
(1) % of debt shifted. Full info: Best Balance Transfers (APR Examples)

Balance transfer GOLDEN RULES:
a) Repay at least the set monthly min, or you can lose special rates.
b) Always clear the card/shift again before the 0% ends, or rates jump.
c) Don't spend/withdraw cash on them - it's rarely at the cheap rate.
d) Unsure what to pick? Use our Which Card Is Cheapest? tool.
e) Check if you can use existing credit first. See Credit Card Shuffle.

4. Get a 0% loan for up to 41mths using specialist credit cards. Some balance transfer cards also offer money transfers, where they pay money into your bank, so you owe the card firm at 0% instead - useful for clearing overdrafts or as a small loan. The top picks below contain the longest and lowest fee on 0% money transfers we've seen.

- Virgin (eligibility calc / apply*), 32mths 0%, 1.69% fee (min £3 - lowest fee we've seen on a 0% card). 19.9% rep APR after.
- MBNA (eligibility calc / apply*), up to 24mths 0%, 1.99% fee. 22.9% rep APR after.
- Virgin (eligibility calc / apply*), 41mths 0% (longest-ever), 4% fee (min £3). 20.9% rep APR after.

Money transfer GOLDEN RULES:
a) Ask the new provider to do the transfer. Don't withdraw cash to do it.
b) Never miss min monthly repayments and clear the debt before the 0% ends or the rate rockets.
c) Don't spend/withdraw cash - that's costly.
d) To replicate a loan, do a standing order so you're sure to clear it within the 0%. Full info & other top picks in Money Transfers. (APR Examples)

5. Get near-perfect rates abroad, every time. If you've September sun planned, or any other trip, bag a top specialist credit card now. Most plastic adds a 3%-ish fee when you spend abroad, but a few specialists don't, so you get the near-perfect rate banks get. Full info in Top Travel Cards (APR Examples) - here are the hottest (which can take 1-2 weeks to arrive):

- Long-term winner: Halifax Clarity (eligibility calc / apply*) has good feedback and a) it's a Mastercard, which usually wins on the underlying exchange rate - see rates compared b) it has low charges for cash withdrawals.

- Slightly cheaper at ATMs:
The Creation Everyday (apply*) is similar, but cash withdrawals are a touch cheaper, though we've little feedback (let us know).

Overseas cards GOLDEN RULES:
1) Clear IN FULL or these cards are 18.9% and 12.9% rep APR.
2) Pay on the card - it's cheaper than withdrawing cash as you usually pay interest on them even if you clear in full. Yet Halifax and Creation still beat most bureaux.

Profit from the credit card price war
There are some scorching credit card deals out there - but you should never borrow unnecessarily

6. Get PAID up to 5% to use a credit card. With cashback cards you are literally paid to spend, but set up a direct debit to repay IN FULL each month or the interest kills any gain. This is one market where deals have weakened over time, but you can still gain (see Cashback rate cuts for info on cuts and why they've happened).

- Fee-free: Amex Everyday (eligibility calc / apply*) 5% cashback for first three months (max £100), then 0.5% on the rest of the first £5k spent in a year, 1% on £5k+ (22.9% rep APR).
- £25 annual fee but better for big spenders: Amex Platinum (eligibility calc / apply*) 5% cashback for first three months (max £125), 1% on the rest of the first £10k spent in a year, 1.25% on £10k+ (28.2% rep APR incl fee).
- Top fee-free non-Amex: Asda Mastercard (apply*) 0.5% on all spending, 1% in Asda (19.9% rep APR).

See all best buys in Top Cashback Credit Cards (APR Examples) and, for alternatives, Airline Credit Cards and Credit Card Rewards.

7. 35+ tips to boost your credit score. You need a good credit history for the top cards above, yet credit scoring's like going on the pull, so you can make yourself more attractive. For what to try, see 37 Credit Boosting Tips. Also, find out how to check your credit score for free.

8. (Re)build your credit score AND get a £20 Amazon vch. If you've a patchy or limited credit history, you'll struggle to get the cards above. However Aqua has cards even some with past CCJs & defaults can get:

- Aqua Advance (eligibility calc / apply*) gives a £20 Amazon voucher after two months, as long as you use the card at least once, pay on time and don't bust your credit limit. Used correctly, it's a good option to rebuild your credit score.

- Aqua Reward (eligibility calc / apply*) gives 0.5% cashback on all purchases & is cheap to spend on abroad as there's no exchange fee.

Both have a hideous 34.9% rep APR, so repay IN FULL to avoid interest and never bust your credit limit. Loads more help in Credit Rebuild Cards (APR Examples).

9. Beware rep APRs and 'UP TOs'. All the cards above are 'representative' APRs, meaning sadly only 51% of accepted customers need get that rate - the rest can be charged more.

Some cards offer 'up to' a certain number of 0% months, so depending on your credit score you might not get the full length. The only way to know is by applying. As a loose indication, the higher your eligibility calc score, the more chance you have of getting the full length.

10. Do you really NEED a credit card to borrow? If you're just funding an ongoing lifestyle this is the worst type of borrowing as it means you're living beyond your means and risk a debt spiral. Use the Free Budget Planner, stop spending and cut your cloth accordingly.

This article first appeared in the weekly email on 24 August 2016, and was updated on 30 August 2016.