DIY, shop around, heckle / bargain a little - or get your g/f to do it, they love it!
Eg. Recently spent $40 on an oil change, including the oil filter and tools - synthetic 10w40 hi-perf. oil, valvoline filter, wrench, change pan etc.
Also, when you are constantly living on "stuff all money" - it makes it easier to get stuff cheap - be nice to people and do favours helps also!!!
mostly obvious stuff but it works