Hi there. I did it professionally for many years when I was younger. Its one of those things that when you watch it in a video you say to yourself "wow, that looks easy, I should be able to do that" The thing is that it is like an art form and there are tons of little nuances and tricks that are not being seen in the video or being explained by the person doing it. Like everything else it takes A LOT of practice to get good at it. It also takes a TON of skill to do any window with compound curves in it. If you'd like to try it out I'll offer up some advice as I do encourage people to try things for themselves to learn.
1. Clean the ever living shit out of the windows. This means scrape the windows with a single edge razor blade using soapy water. Use a soft dish scruffy pad on the back window to not damage the defroster obviously.
2. Get one of those pump bottle from home depot that are used to spray insecticides or plant food, you can find them in the garden department. After 1 window of trying to use a squirt bottle you'll be ready to quit.
3. Buy enough tint. When you are learning, you will mess up alot. Do not continue to use a piece after you've crimped it. Its done at that point. Buy 2.5 times what you calculate you'll need for the car.
4. Windows without frames like ours are actually alot easier but you'll need to leave a good gap around them. If you are an expert like me
you can do the filed edge technique but even I went through a few feet of film to get every door perfect. I dont recommend that method for the novice.
5. Watch as many vids of people shrinking tint on curved glass as possible. This is the single most hardest thing to learn in window tinting. you need a variable heat heat gun. cant be too hot or you'll melt the film.
Or just pay someone 100 and change and let them do it right for you the first time
Hope this helps, I could go on for another 1000 words but I'm tired of typing lol