But seriously, YouTube. Have the manual for reference, and watch someone else go through what you want to do. Ideally more than one someone else, actually, if you can find the vids. Build threads here and other forums are great, too; I’ve learned a ton. For your T4R, check out Timmy the toolman on YouTube; he mostly does 4Runner vids, and goes into lots of detail.
^ I think Tim just does 3rd gen stuff, although a lot of it probably carries over to 4th gens. Dude has saved me a TON of money over the last couple of years.
Watch youtube videos, start out small and work your way into bigger projects. Do an oil change, then brakes, then balljoints, and before you know it you'll be doing transmission swaps.
Pro tip: buying the right tools, even from harbor freight, makes things WAY easier.