Shareholder contract review?

Hi all, been offered an Exec position in a small but funded start up that I very much want to pursue esp because I will be receiving founder shares. I have previously lead teams in other Tech companies and departments so always had some shares ; RSUs etc. wherever I went but I never have dealt with a Shareholder contract etc. given the enormous task at hand I want to make sure that my docs are reviewed by someone who has knowledge when it comes to these type contracts. Now my question is; There is a ton of corporate lawyers out there but it seems hard to really know what specialities I need to look out for? Has anyone been through this before and can tell me what I should be paying attention to and where to seek advice? thanks