We use 1/2" poly tubing with Bowsmith 1 gph emitters, with a tee at each tree and loop of tubing with 4-6 emitters per tree. You can expand this by adding more emitters and enlarging the loop. The Bowsmith emitters are found at irrigation supply houses and the only ones worth messing with; the Digg ones from Home Depot are unreliable and about the same cost. I guess all this is dependent on how much critters are chewing on your tape and tubing; if it's bad you might want to consider PVC pipe.

Applenut

Is there a good tutorial on setting up simple drip irrigation?
I want to eventually setup one for front and backyard. Doesn't need to be timed. I can turn it on everyday, maybe some manual switches so left backyard side, right backyard side, veggie garden in back can be turned on separately based on water needs (think these would be 'Control Valves').

I saw a slightly very complex one that showed the different emitters and various things you can use like Backflow regulators and Pressure Regulators, on many pages:
http://www.irrigationtutorials.com/dripguide.htm

Not sure I'll remember all that though :)

I'm a relative beginner, and I put in a drip irrigation system last summer similar to what applenut described. I had a good experience with this website, after the big box stores were useless. They have some good information about what you might need. Unfortunately, I think you really do need a pressure regulator and backflow preventer. I used perforated drip line around my trees, but I think the 1 gph emitters would probably work better, or at least faster.

Here is a link that might be useful: Drip Depot