Get one with 0% for longest etc etc, shop around and you know the best when you see it.
When you use it!! Hehe, no seriously, you lose out when you begine spending on it and can't pay it off quickly. Best thing to do is say, if you can't afford to pay it off in the next month, it's too expensive to get. If you KNOW you can pay it off quickly, no problem. Don't go putting 2k on it unless you are sure you can pay it off and are happy paying the interest. Make the most out of the 0% interest while you can, then my advice would be to enter the interest period with nothing outstanding, and keep it that way. Great for emergencies so worth having one.
Good. I have 2, both used in emergencies, or i'll have the money, but buy with credit card and pay it straight off, that way, you can benefit from the insurance on the product which you get by buying it with the card.
Plan how you are going to repay it as fast as possible. If there is no visible way of repaying when you're back, then you can't afford it and you're on the way to getting in the vicious circle of credit card bills building and building. You can end up paying £100 per month, yet your bill only drops by £10 or £15 per month.
They're good if you're good. They're handy and can pull you out of circumstances like losing your wallet, forgetting your debit card at the petrol station etc.
bongo