Do many free initial consultations, with different lawyers! Each will have a different take, adding something to your understanding, unless you happen into the world's best at these issues on your first inquiry. Maybe you'll then rack up fees with one... but maybe instead you'll just know how to protect your rights, if the venture takes off, and then return to that lawyer years later to collect. (No out-of-pocket costs up front.)
Request them from a few attorneys to get a better array of choices. As with anything, attorneys come in a wide variety of abilities and styles.
Recommendations are optimal. Also try to get at least one who is agressive in the mix. If they all corroborate one another, then that in itself is a statement.
The difference in suggested recourse and the outcome itself can be night and day depending on your counsel.