1) You have to make a choice: store vs Pro.

Pro is better, but if you need parts lowes & HD, etc only few
minutes away vs week(s) mailorder.

Pro stores in my area are out of they f***ing mind. They
are trying to sell box of Hunter PGPs for $449.

2) Pipe: Sched 40 PVC vs poly.

Sched 40 is more rigid, but must be glued. You must wait for
Sched 40 PVC to dry before testing. Sched 40 joints could
and will crack if it gets below 32F.

Poly easy to assemble (couple of clamps) . Better in the cold
climates, can be pulled under your lawn, can do some angles.
etc etc. Some people claim it does not last as long as PVC.
(Never seen this issue)

3) For poly you could trench your yard, or pull under.

4) For poly you could use Ts or saddles.

5) Timer not as important as many people think.It used to be
that Hunter Pro-C was the king. Now it seems that RainBird
ISMs just as powerfull. ISM9s gives you 9 zones for $55,
ISM6 - 6 zones for about $40.

And timer can be easily changed. So if you only need = 4 zones
cheap $17 rainbird would be just fine.

6) Backflow, get Febco ( they look cool anyway )

7) Are you comfortable with attaching pipe to the mainline?
Cut the right side! Not kidding....

8) Attach blowup adapter for compressor.

9) Automatic drains vs manual.

etc etc etc