Look in national papers they publish interest rates for accounts best % rates. Shop around and get a good deal, afterall banks, building societies want your custom. There are some good on-line rates to through internet banking.
Some financial advisors are good too, they will recommend accounts and not charge you, but get commission from the banks. or go into branches and ask them what account have you got, and compare them to each other and play them off each other.
Take advantage of your tax free savings first. Look at the long term, e.g. tracker funds. Look at shares too, in a good company, worth a look.