As in your own flights? Don’t overload yourself at the beginning, you’ll burn out fast.
I wouldn’t join more than 4.
Make sure you’re interested in flying where that VA goes. I would also take a look at how the staff carry themselves in their thread and on the forum in general. Organization and professionalism are important, especially among staff. This gives a VA a sense of being well-run.
Make sure to have a decent amount of IF experience, it’s likely your pilots will have questions. Have an idea for the staff team to want to run - it’s far easier to do the busywork with people you already know rather than new people. Starting a VA is way more work than I think most people realize so be ready to push through that. Also, know how to accept constructive criticism and build off of it.