Hi Michelle ---
I was an independent for many years. I don't think that there is any hard rule on how long you are programming...consulting is far more than just being technical. I knew a guy who did really well at it while being a technical disaster. How? See below:
What you do have to be is a good self-promoter. You also have to master walking into a potential client with steely-eyed confidence. Clients get nervous about you if you're nervous.
As to what you should learn: Learn the theory behind what you're already doing (OOP,RDBMS theory, Codd, etc). Learn a server database like SQL Server. Learn VBA at the least, if not VB. Learn enterprise development concepts.
Finding a partner who is more outgoing is not a bad idea if you know someone you can work with. Partnerships are like marriages.
Good luck!
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John Koziol, ex-MVP, ex-MS, ex-FoxTeam. Just call me "X"
"When the going gets weird, the weird turn pro" - Hunter Thompson (Gonzo) RIP 2/19/05