The general entry to this niche world is Cyborg4Life on YouTube. There is an extensive catalog of content you will need to check before anything. You are young you can use that as an advantage.
Answering your questions:
Where do I even get started?
Well you are already here, meaning you have been doing your research, that's good. As I said Cyborg4Life is a must for newbies. Watch his content and take a look to his interviews, solid content.
How much money should I save up before attempting to begin my LL journey?
This may vary from place to place. Cheaper places are often terrible, I wouldn't advice to anybody going to India or Turkey for this surgery. Yes is cheaper, but your chances of getting crippled are extremely high. Avoid Livelifetaller Wannabetaller or Turkey in general, those ads are fake and people who go there are literally risking their lives, in fact avoid any "doctor" promoting LL as if were ordering a Pizza from Dominos. One of the best places cost-benefit is Greece, with Dr. Giotikas. Anyway you need to do more research on Doctors. Money wise you will need in the cheaper high end something between 50k to 70k. There are cheaper options in Vietnam too, Doctors there are reputable, but as I said you will need to do your research.
Any advice
Be conscious of your limit. Theory is one thing, but real life is something different. I would advice you go for femurs to a 7cm max. That's a safe range and your recover would have a higher range of succes. I wouldn't suggest quadrilateral for cosmetic reasons. Ever.