Before you go for a fitting, get comfortable with your technique.
1. find technique - lessons, Super SAM, TOMI, or other evaluation aid, Pelz, Utley, Tiger-like method, O'Brien, etc.
2. Does that technique work for you?
3. Make it instinctive
4. Get fit. Fitting should involve which putter you aim best, length, lie, etc.
For a unique experience, you might try this guy if you're ready to throw some bones at them --
www.edelgolf.com