How do you determine category goals for roto?

[fridayfrenzy]

Lets say that it is a 5 x 5 season long roto with 12 teams, and a lineup of

C, 1B, 2B, 3B, SS, OF, OF, OF, Util, Util, SP, SP, RP, RP, P, P, P, P

When I am drafting, I want to have a goal in mind of how many HRs, Ws, ERA, AVG, etc. my team will need to be near the top of those categories so that I can draft accordingly.

This would be simple if I had the same league settings and could just base it off a prior year, but if this is a new league how do I find out what my category goals should be? Is there a formula or benchmark?