The most important thing you should understand is the distribution of the equity (e.g Someone else has 70% or you are the biggest shareholder with 30%?) and the rights (power of decision) that each shareholder has.

Protection is, in my opinion, created be three things: legal rights (laws and contract), trust and information. You need to focus on mastering the three of them to leverage them in your favor and your protection.

PS: it requires more info to give a good answer