None, if you are just starting to earn elite status. Take UA for example, for the first 24999 miles you fly, you are nothing but a general member.

Chances of getting upgrades depends on a lot of factors, levels of EARNED elite status being one.

Like others said, you need to spell out more details. Some domestic routes do not even have first class seats. Lots need to be factored in, your routes, choices of airlines, fares of tickets (coach, business...etc). There's no flat out answer to your "simple" question.

Welcome to FT!