So let's say you for some odd reason follow my guide to try something new, so what you do first is buy said items, then head to mid lane, don't try to farm dangerously, if the enemy is a ranged attacker, don't try to farm as often don't use E, if you're getting hit, be sure to use W and for farming use Q to escape tight situations, like an enemy gank
farm until you have enough gold to buy the next set of items

Ok so you should have bought the items i specified, next go back to your lane and farm, you can farm a bit more agressively now, since you are harder to kill now, this phase is pretty boring because you should not try to tank in teamfights until you at least have Dead Man's and Thornmail, so just keep farming for now

You made it, you have 3 or 4 big items, now you can finally tank
Tips:
-Only tank if there is a friendly attacker with you
-Don't think you can't be killed, you can (experienced it myself)
-if your team needs tanking quickly than use your Q spell to get there fast
-with this build i have won several 1vs1s so you should be able to,if the enemy isn't fed and mostly does AD just go at them, use E and W keep hitting, they won't kill you, but they'll think they can so they'll keep attacking you and they will try to run if they get low on health, use Q to catch them and E + w them again if Q doesn't kill them

If you have read the whole thing than thanks for following my guide, now go win