i'm going to look for some fabric for a 4pp. what's the best kind of fabric? what's the min and max for the repeat? thanks in advance

you can pretty much cut the squares any size you want. I've seen them any where from 4" to about 10" (so 4 2 inch blocks or 4 5 inch blocks + seam allowances) You can let the size of the repeat be your guide.
Often the blocks are fussy cut to get the showiest squares, so you are going to have some wasted fabric. I would take a couple of mirrors, tape them to make a hinge and audition the fabric with the mirrors.
Hmmm, not much concrete advice ;-)

http://www.quiltingboard.com/t-136599-1.htm
most any busy fabric will do for four patch. posies are flowers of course. doesn't have to be floral though. paisley or other wild print makes great four patch quilt blocks.
24 inch repeat is good but i've seen some done with 12 inch repeat. the farther the repeat is apart, the more individual blocks you will get.

There's no need to fussy cut for a 4PP. You'll only waste fabric and part of the beauty of this technique is the random kaleidoscope patterns you create.

The longer your repeat the more blocks you will have that will be different. The closer the fewer. Though you can use more than one set of repeats. If so, just cut an inch off before you start the the next slice and set so you and don't have the new stack identical to the first.

And of course, you need to consider how large you want your quilt ... bed size? wall hanging? small table topper.

Generally the larger your print the larger you might cut your blocks.

The one I did didn't have a very large print so I cut my blocks 3-1/2" which made 4-1/2" unfinished 4PP blocks to work with.

I bought a Fat Quarter the other day ... and it has 4 repeats within it. I've been eyeing it up and thinking I just may stack it up and make a few 4PP and then do something with them!

thanks for all of your advice. it's really helpful.

I took a class for this pattern. One lady had a fern print that only had an 8 inch repeat and was basically two colors. She set the blocks on point with sashing. It was a *very* striking quilt. One lady used a striped floral and it turned out very cool. The four patch posie really gives you a lot of design options.

those sound very interesting. got my creative juices running. thanks.

I have the pattern and when I bought the fabric the LQS helped by cutting the pieces so I could see how it was done. I called and asked them if they could help me since I was traveling 8 hours to get there - they really made sure I understood how to do it. Now need to cut it out. The top of my absolutely going to do this next list. LOL