There are many ways of finding cheaper fares. One trick that not many people know about is the use of rovers and rangers which can cover wide areas and allow multi journeys. These can be way cheaper than return tickets, especially if you want to make multiple journeys within a week. Always worth checking here: http://railrover.org/
Also NEVER EVER book with thetrainline as they charge a booking fee. It is ALWAYS cheaper to book with a main operator especially as they basically all use the same software for searching fares and booking and some even offer Nectar points
There are also a good number of hidden fares that nobody ever tells you about like Virgin offer a weekend day return discounted ticket to London from the Midlands and North West that includes a day travelcard for the whole London area which is great if you want a Saturday in London. The trouble is you can't actually buy it off the Virgin website and have to use one of the other operators sites!
Finally, and I may be in a minority of one here, but I believe railcards are fundamentally discriminatory on grounds of age, disability, family status and location and in our modern world of equal rights (which I completely agree with) they should be banned outright with everyone paying the same price.