the more direct debits you have (without missing a payment) the better. Works the same as getting a credit card.
who do you bank with? i found out that building societies dont give you a credit rating. i had been using my atm card/cash to pay for everything for 4 years. and it actually made me have NO credit rating- so therefore a poor one.
fast forward 18 months and now its excellent- so check your bank, direct debits, electroll roll, how much assess to money do you have- the more you have the worse it is, so if you have lots of credit cards/store cards but dont use them- close the account down.