Don't Start From Scratch
Other Vim users have suffered so that you wouldn't have to.
(Part of the Tips For Learning Vim series.)
Some people might like the idea of starting with a blank slate for their Vim config, and then adding as they go, and I see the appeal in that, I get that, and (to quote Gary Vaynerchuck) I respect that.
I'm not a patient person though. I want full Vim fabulousness, and I want it now.
A bunch of veteran Vim users have already spent lots of their time cultivating Vim configs that make Vim behave in useful and magical ways. I used one of those configurations as a starting point and tailored it from there. This made a lot of sense for me and helped make me more productive sooner.
The few people I've helped switch to Vim have started by forking my dotfiles repository just to leverage the vim config that's in there. We shared a Textmate background, and we were all doing ruby development, so it made a lot of sense. Since we started off with forks, it was easy to use github to share additions and tweaks we made over time. We'd send each other messages like "Hey, I just added a plugin that does snippets just like textmate - do a pull!" and everyone would benefit for it. Good times.