Which variation(s) should I start playing the Ruy Lopez Opening?

I have decided to play the Ruy Lopez Opening which is recommended to beginners in a lot of videos. But I don't know how to start.

@1
Just play it. Think carefully. When you lose, analyse.

The first step is this: get a thin book on the Ruy, like Barden's old book. Play it in blitz/quick , take your wins and losses in stride and after each game analyze the game and look up the variation in the book to get the general idea [not the specific moves] how to build up your position next time. At some point you'll start to see more ideas. Then get some book of annotated Ruy Lopez games and add a 3rd step: After each game also play over some annotated GM games in the variation.   -Bill

There's a lot to be said for starting with the exchange variation, as favoured by Fischer at one time. You have to know that White can't take the e5 pawn immediately as Black wins it back with Qd4. After 5.O-O you get a nice open, unbalanced position which will teach you a lot, and is probably less confusing than the slow, closed positions common in the main lines.

Arkhanglesk and Neo-Arkhangelsk as Black, learn everything as White if you're going to make this your primary opening. Just make sure you are also prepared for French, Russian, and Sicilian players, as you're statistically more likely to encounter one of those than the Ruy Lopez, especially at higher ELOs. However, I wouldn't even recommend the Ruy Lopez to people my level and below. There is far, far too much to remember. I'd recommend the Scotch or the Italian (I'm a little skeptical even of this for beginners), Reti, English, London System. Try to avoid theory until you hit 1050 or so, and then start learning very basic theory (Italian, Russian, more complex English lines, maybe some hypermoderns such as KID, Modern, Pirc, and Alekhine's), and start learning actual theory (except the mainlines of the Queen's Gambit + variations, Indian Game + variations, Ruy Lopez, and Sicilian) at 1300 or so. And then once you hit 1500, start learning all the theory you can. But at lower levels its more important to learn opening principles and blunder prevention.