I've always used the look three balls ahead method just because that is the way I was first taught to do it. Obviously that changes when there are trouble spots. Over the years I have learned to look over the whole table and try to go into the first shot with a plan. That way you have a solid idea throughout the whole rack and if you get out of line, you can find a way to get back in line.
I know a lot of the top male players that I have talked to work from the last ball and get a good layout. Johnny Archer did a tv show, sorry I can't remember what it was, and he explained the way he looked over the rack and planned it out. It was really interesting. I am going to have to look up what show it was. *edit* I found it. It was on the History Channel on the show Modern Marvels in an episode titled Bullseye. I haven't searched extensively on the site to see if you can watch a clip but you can do so
here.
Of course, it depends what game you are playing. I am not very good at seeing patterns playing 8ball. That is part of my frustration with that game. Straight pool is another game that pattern play is important, but that game isn't my strong point either, although it is better than 8ball! I know top straight pool players can pick out their break ball and build a pattern around it very early in the rack.
How do you select your pattern? I am interested in how others do this.
Sarah