When you are freelance it makes sense to travel cheaply (I book meetings at times where I can travel off-peak with my Network Railcard etc).
A while back I also realised that I could save money on some locals journeys by extending the ticket and breaking my journey early (i.e. getting off the train at my destination - not where I had bought the ticket to!)
For example, where I live in Ash, Surrey an Anytime Day Return to Guildford is £7.60. An Off Peak Day Return to Guildford is £6.10 but only valid from 8.45 AM.
However, an Off Peak Day Return to Shalford (one stop beyond Guildford) is £4.80 and valid from 8.30 AM.
I am reliably informed by an acquaintance who works as a train guard that tickets are priced due to demand for that destination. In short, if you are travelling to a hub station explore all the tickets to one stop beyond your destination. You can save more than 1/5 just based on the example above...
When I first learnt about this I lived in Aldershot and the cheapest ticket I was aware of for certain journey times was from Aldershot-Farncombe if I was going to Guildford. Now I'm in Ash (one stop further along the line to Guildford) it's to Shalford.