Want an honest answer? If this is your first time, don't try it, you will at best reach silver/gold, and playing at this level isn't that much different from normals, i mean, you can try, but don't be surprised if you'll rank yourself low.
Before starting ranked go to op.gg, and see your CS score, if your cs score is at least 6,5 (speaking of lanes), then you can start rankeds, because if you don't gather gold in your hands correcty you will just be a burden and every win will be either you got carried/the enemy team was REAAALLLY bad/you got lucky, and those are not good ways to win, because you won't improve at all and you'll just bounce up and down a couple of divisions without EVER moving forward.
What you need to do now is to learn the game, watch some streams, watch LCS, watch the videos riot published where they comment teamfights during important tournaments, try to reverse engineer that and learn why, how and when they did that.
Learn wave management, learn the mechanics and practice them, your role thoroughly, rotations (and this includes map pressure as well), learn how to not waste time and get the maximum advantage possible out every action and every second, learn how to trade, learn how to win your lane, learn how to bring your advantage in the right parts of the map, and even play when you're behind.
If you jump into rankeds without a proper preparation you'll simply ruin yourself because this game punishes more your own errors than enemy misplay. (just a small example: wrong wave management can make the difference between losing or gaining 12 minions, and in the long run it will make you lose at least half of your supposed farm, now imagine you could magically double your gold once you are mid game, this is how much you missed. And i bet you, right now, don't even notice that.)
There are also plenty of youtube channels that specialize in high level replays, just search "lol replays" on yt.