I can't think of anything more likely to cripple a character's effectiveness than commitment to a particular career path. I won't even set myself up to follow feat trees unless the starting feat is flexible enough, a character has a lot of them, or the tree is plainly appropriate to the character concept regardless of what happens. Rangers should take archery feats, knights should take mounted feats and invest in mounts, etc. Otherwise, I build exactly the way people build themselves in real life - in response to their experience and opportunities. That way, you're never caught regreting "wasted" skill points or feat slots selected on the basis of an ideal career path that circumstances wrested from you.
All my characters are liberal arts majors - employable whatever happens in the economy!