On TRT for the last 8 years and know many doctors in my area, so I can give you an idea.
The first question is, why do you think you need TRT. What are your symptoms? That is what any doctor is going to ask and you need to be honest with yourself because it is trendy to blame every little thing on low test.
The best place to start is your GP and see about a referral to a specialist. Better yet, if you have access to an integrative doctor in your area, start there. They are much more informed about gut health and other areas that impact test levels and can also prescribe medication as needed.
At minimum you want total test, free test, SHBG, LH, FSH, e2 (if possible), thyroid, and a CBC w/lipids. Start there and see how things come in and look to determine if there are any lifestyle improvements you can make to help.
I'd avoid the money making clinics at all costs. They typically have a cookie cutter protocol that will include an AI and HCG along with a higher than necessary amount of test and then end up having to correct things.