Starting again

I'm not an expert, but I think that you should spend a little on each card every month (keeping them active) and paying off the debt in full when requested if you can. This will take some effort, if your not particularly good with your finances.

I don't think just having a credit cards and not spending anything on them will help your credit rating.

From my experience it really depends - it is seen favourably that you have available credit but are not using it (by having cards with 0 balance) - yet it is sometimes unfavourable to have open accounts not being used.

From a recent credit check I did, the advice given was to close credit accounts I was no longer using.
Although it can be a good idea to do a small amount of spending and repay in full each month, if you have had bad credit previously usually the best thing to do is stay away from borrowing for 6 months or more and your rating will slowly creep up.

Ultimately I would definitely cancel one of the cards, keeping the account you have had for the longest time (as recently opened accounts also don't look great to lenders), or the one with the lowest % interest.
Only keep the other one open if you are confident you won't be tempted to overspend on it!