Path to Developer?

Somewhat similar to what others have said, I think there are five general components to going out on your own:

1. Development experience/track record. Anybody who is going to invest money in your deals wants to make sure you know what you are doing. Have you developed this product type in this market before? Do you know what you are talking about with respect to project cost budgeting, schedules (entitlement timelines, construction), structuring (JV agreements and debt/capital stack). Given that most "real" development deals take 3-5 years to complete, you generally need to get some significant experience under your belt.
2. Local market expertise. Investors don't just want to know what you are going to rent a building for. What are vacancy rates? What's the competitive supply pipeline? What are spot cap rates today, and expansion over the development cycle? What are PSF/per door sales prices, both for completed product and land? What are market ROC %s and spreads between those yields and current cap rates? You need to have answers to all these questions.
3. Ability to raise equity. You're useless unless you can raise the money. Whether it's through personal connections, industry relationships, cold calling...unless you can fund it, you aren't building it. A lot of shops have a BD/equity guy whose sole responsibility is this piece.
4. Ability to source deals. Similar to #3, unless you can find deals with attractive structures or returns, you aren't building it. Some people generate through broker relationships, some through cold calling, others by knowing a submarket better than anyone, or a combination thereof.
5. Optimism. This kind of outlook is critical for a developer. In the 10 or so development deals I've worked on, none appeared to be clear cut home runs at inception. If we used the conservative underwriting assumptions, not a single one would get out of the ground. A big part of development is learning how to reasonably cook numbers to help sell the deal. Provided you are using leverage responsibly and respecting general market trends, a positive visionary attitude makes a huge difference.