The old adage “neither a borrower, nor a lender be” is no longer fit for purpose in our modern world. While some find that tough to stomach, we need to face facts. Unless you’re super-rich, you’re going to need to borrow to buy a house or go to university.

So the real key these days is learning when it’s right to borrow, and how to do it. The nightmare scenario is those who need debt to fill a regular gap in income. That’s just asking for trouble – and, sadly, trouble will oblige.

Yet if it’s a planned purchase – be it a new kitchen, car or home repairs – and you keep the amount to a minimum, do a budget to ensure you can afford repayments, pay it off as quickly as possible and ensure it’s as cheap as you can, then it’s a reasonable choice. So here’s the 10 things you need to know...

1. Spend on a credit card, clear it in full, to get a month interest-free

If you just need short-term borrowing, use any major credit card (except Lloyds Advance) to pay, then repay it in full at the next statement and there’s no interest. Don’t withdraw cash though, that will cost.

2. Borrow at 0% for 18 months with no fee

There’s no cheaper way to borrow than interest-free. So if you've a decent credit history, consider a 0% credit card deal.

However, only do this if you can ALWAYS fully repay or transfer your balance before the 0% ends, or the rate you pay will rocket, wiping out your savings. Diarise when the deal is due to end and act in advance.

The longest 0% deals for new borrowing (don’t confuse them with debt-shifting balance transfer offers) are Tesco Clubcard Card (tescobank.com) and M&S (money.marksandspencer.com) which are both interest-free for the first 15 months. Nationwide (nationwide.co.uk) gives a longer 18 months, but only for its existing FlexAccount holders. Ensure you pay off in full or you’ll pay 16.9%, 15.9% and 12.9% APRs respectively.

3. Borrowing if you’ve got savings often doesn’t add up

Do the maths. £5,000 in a top savings account only pays around £125/year interest after tax. But borrowing that on an 18% credit card can cost £900. So unless you've super-cheap debts, it usually pays to use the savings instead of borrowing. This can often work with mortgages too – for free help to decide and calculators see mse.me/repaymortgage

4. Poor credit scorers can get 0% too, but take care

Capital One's Balance Card (capitalone.co.uk) is 0% until November on shifted debts (not new spending, 1.7% fee). However, it then jumps to a HUGE 34.9% representative APR.

Usually, this should only be a route to cut existing debt costs. But as it's the only cheap deal for poorer credit scorers, if a payday loan's your only other option, shifting existing debts to it to temporarily free up space on other cards beats that. I was in two minds about whether to include this as it can easily go wrong, so please be incredibly wary, and ensure you can clear it all before the 0% ends.

5. Flogging unused stuff beats costly loans any day

If you're looking at costly cards, or worse, payday loans, sell or even pawn unused items to raise cash instead. Use my www.mobilevaluer.com tool to compare prices if you’re selling an old mobile, flog unused stuff on ebay.co.uk, gumtree.co.uk or local car boots.

6. The cheapest loan is 6%

If you need bigger borrowing and want a fixed disciplined repayments – thederbyshire.co.uk charges 6% for loans from £7.5k to £15k. sainsburysbank.co.uk is 7.7% for £5,000 to £7,500 for 1 to 3 years and 6% over £7.5k for 1 to 3 years but needs a Nectar card.

Be warned: these are 'representative APRs', so only 51% of accepted applicants must get that rate – others can pay more. Outrageously, to find out your rate you need to apply and that marks your credit file.

So, plaudits to Nationwide’s (nationwide.co.uk) 6.8% APR (6.3% for existing customers) above £7,500, as it tells you your rate without a formal application.

7. Flexible loans are possible

If you're over 26 with a decent credit score, peer-to-peer lender Zopa.com triumphs. It's cheapest for smaller loans (eg, 10.1% for £3,000 compared to cheapest normal loan at 12.8%). Plus it lets you overpay without penalties - rare in the loan world. Rates depend on your credit score, but you can check what it'll charge without a credit file hit.

8. Government 0% crisis and budgeting loans

Two Jobcentre 0% loans for up to £1,500 are available. Crisis loans are available to anyone (savings caps apply) for real emergencies, or if you or your family are at a health risk, eg, your roof’s fallen in. Budgeting loans are only for benefits recipients, but allow spending on a wider range of items, such as school uniforms. Sadly, each region has limited cash, and if they've run out, you won't get it.

9. The cheapest small loan involves playing with plastic

If you need a lump sum, normal credit cards can't help. However, Virgin’s Balance Transfer Credit Card allows 'money transfers' to your bank account at 0% for 20 months (20.9% rep APR after that) for a one-off 4% fee. In other words, it pays the cash into your account and then you owe it instead. Don’t try it on other cards, or it’ll cost a fortune and be very careful to follow the right process with Virgin – full help at mse.me/plasticloans

10. Payday loans can be hellish - avoid

While many rant about APRs of 5,000%, that's not what really scares me. Over a month, £200 costs £60. The problem is many of these firms nastily encourage you not to repay, so the debt rolls over and costs explode. I'm hearing more and more horror stories along the lines of "I borrowed £100 and now I owe £900". Don't risk it. Try your local credit union instead.

And, finally, for those who already have debts and are struggling, or even missing nights’ sleep, remember, free one-on-one help is available, and it works. They’re not there to judge you, they’re there to try to help. The Consumer Credit Counselling Service (cccs.co.uk), Citizens Advice (citizensadvice.org.uk) and National Debtline (nationaldebtline.co.uk) can all help.