How should we prepare for our seed round?

We are a young startup based in Austin, Texas. So far our startup is comprised only of a small number of cofounders who together have been working on a prototype. We have created a minimal viable product, gathered early adopters feedback and developed a marketing & distribution strategy.

We are now planning to launch a seed funding round. How should we bring our venture into "the right shape" in terms of company formation? Legally speaking, what's the best way to prepare such a financing round?

Thank you for your input