I don't smoke.
I drink a little but I'm pretty sensible compared to the rest of the mid-20's bracket in England, and even then it's not weekly or something I need to do to have a good time, which saves a lot of money. Establishments are legally entitled to give you tap water for free here, which saves a few quid on mineral water. I also never get into either buying rounds, or buying random girls drinks (chode move!), even if they ask (my sister used to go out with no money just because she knew she could get randoms to pay for her all night, lol).
I never buy magazines now as using Reeder on my iPhone (RSS feed synced to Google Reader account) brings me all the relevant information I want, as well as the usual website browsing and forum posting. I don't have a car, although I would like one, but I would be following Uncle Erik's model rather than getting anything too flash.
Put media I want in my Amazon basket and move it to the 'save to buy later' area. Then, I check in now and again and it tells you what has gone up/down in price and by how much. A very easy way to nab things like CDs and BluRays even cheaper than the usual online retail prices. I also rarely buy things on release unless they come out cheap to start with, e.g. I want Star Trek on Blu Ray but it's still £17, and I'll wait until it hits that £10 mark a lot of the other BD discs go for before I grab it.
Look for good deals/buy used on A/V equipment. I got my TV at clearance prices purely because it was a 'last year' model, even when the series that replaced it was inferior. Ditto for my Blu Ray player (even made it Region Free, for free!). I got my DAP used off eBay via a Head-Fier selling there for less than new. I will probably look to get as much of my audio rig 2nd hand as possible, although some things like the DAC I want (the Yulong one) aren't too much of a hit to put me off. Forums with members buy/sell/trades are always great for this, as there's more or less a forum for every interest or craft you can imagine. I know plenty of small-time buy high-quality guitar builders, for instance, and could get a custom made instrument for less than a high-end retail one that would blow it out the water.
Avoid impulse buying.
Annually go through my wardrobe and sell anything I never wear/fallen out of love with on eBay. I rarely fail to sell and if not, then it just goes to the charity shop. I also always try and sell anything I want to get rid of, either via eBay or through general Facebook/forum posting. I also take care to check postage prices for the weight of the package so that I'm not under-charging, or over-charging excessively. When buying clothes, although I like to be fashionable I still try and look for stuff in the sales online, especially for things like casual/home wear.
When buying food, especially fresh, get stuff that's in season since it'll be cheaper, and don't get seduced by deals unless you actually need the stuff and are going to eat it. Avoid wasting food by using up leftovers for lunches or chucking it in the freezer. It's worth learning how to throw something together yourself quickly rather than spending way more for prepared stuff too, although obviously sometimes convenience takes priority. Takeaways kept to a minimum!
Work out at home, it's far cheaper if you get the right equipment (i.e. free weights, kettlebells, a chin up bar, something to put on your feet to jog with) and although it does take up a little room, it costs a lot less than a gym membership and you avoid the usual problems of it taking up travel time, waiting your turn for things and getting annoyed with posers who flex in the mirror but never work on their legs, or middle aged women spending hours on cardio machines while talking about how much cake they'll eat when they're done.
I ride a bike to work rather than get the bus.
That's all I can think of right now!
Edited by Somnambulist - 10/2/10 at 1:05pm