There are loads of different drip irrigation systems. You can go home made, or you can go semi professional. Semi pro DIY drip irrigation systems aren't that expensive. If you go homemade (ie punching holes in pipes and milk bottles), you're going to risk uneven watering as the release of water is unregulated. Purpose made drippers regulate the amount of water that's released, meaning you can be really precise. You can also use these in conjunction with a water timer, meaning its completely automatic.
You mentioned as well you're worried about water loss due to evaporation. Drip systems can be installed on the surface, then covered and hidden with mulch. This retains the moisture and stops evaporation.
Other people are mentioning soaker hose/leaky hose. This is a good way to get something set up nice and quick, and is good for starting out and experimenting, but there are two problems with it:
1) There is no regulation. It is just porous pipe. Watering can be uneven and can only really be used in short runs.
2) It is just mushed up rubber. It only has a life of about 4 years, meaning you have to buy more and spend time installing it again.
I would really recommend using a semi pro drip system using purpose built drip emitters. I'll put some links below to help guides on drip irrigation systems from suppliers of semi pro stuff. I'd really recommend having a look. As I said they're not massively expensive (about £70 for a small garden up to £200 for what I would call an average garden with a timer), and when its installed, you take all the hassle away.
Hope this helps guys and girls. Give us a shout if you want to ask anything .