I'm tired of all those irons boosted in gold.
How about using champions' mastery system to be an useful feature.
For an example, after promoting into gold IV, you should have at least 3 champions with mastery 7. Staying in Silver 1 with "pending" status until then.
This way, we can stop a majority of boosted accounts and smurfs, who are to lazy to grow 3 or more champions on a level 7 mastery knowing the fact that this require time and blue essecence.
I'm also tired of taking for the first time champions in ranked games, so a great idea would be to play at least severeal times with a champion in normal games before being eligible to pick it on a ranked game.