I went to law school to do that, but without that you can start by focusing on an area of law called "business associations/corporations." There are resources online to assist law students studying for exams in that class so you can use those to get a grounding in the concepts of agency law and partnerships.

From there you can start to specialize in more specific structures by examining the filings of public companies or scouring the web to figure out how a particular fund you are interested in is structured.

To let you know, it is further complicated in US law by each state having different corporate rules. If you go with Delaware or New York it's probably your best bet for public, but closely held or private companies could be anywhere. As a starting place, most states adopt the Revised Uniform Partnership Act, or RUPA - that is available online through law.cornell.edu

be rich enough to be a limited partner, means you're rich enough to have your own specialized lawyer to review the contract (instead of "I know a guy" "my cousin" "prepaid legal" "general counsel"), rich enough to afford an MBA, rich enough to do a dry run in setting up your own hedge/vc/pe fund

otherwise, I don't know exactly. but I've personally been reading wiki pages on fund structures since I was 18 and not eligible for anything, just dissecting the quiet class systems I noticed. scouring SEC documents, and validating my assumptions with hedge fund lawyers and being an LP when I could afford it later