Anything else i can do?

So i've had bad credit in the past.

3 defaults from 3 and a half/4 years ago all paid off in the last couple of years.

I've got a vanquis card with a £150 limit on which i spend under £15 each month and pay the full balance off when the statement comes through.

I've got an MBNA card with a £500 limit which i spend under £50 each month and pay the full balance off when the statement comes through.

My o2 loan for a phone has finished this month and i have elected for a sim only deal going forward.

So my question is can i be doing more to improve my credit history file to look better to prospective lenders. Should i be getting other credit products to improve.

I'm on electoral roll, never miss a payment anymore.