Wards: Play a bot game, and rush
. Get a bunch of the green and pink wards too. Always keep a pink in dragon or in baron. You can place wards over walls, all it takes is a little practice. Anytime you're chasing someone, or running away, drop a ward in every bush you go thru. With tons of practice, it'll become second nature.
Vs Fed: Play passive. Make the game boring for them, until they mess up. Check what gear they have, and build defensively against that. Ask for help, and never 1v1. You can get a custom game, and feed feed feed, then practice strategies.
Grinding/Specializing: Do both. Pick your favorite roll and champ, and play 20 games with them. Then 20 more. However long it takes for you to sling abilities without thinking about it. Google your champ/role and look at builds and strats across multiple sites. There are even lots of maps showing 'where to ward and when, etc'. When you feel like a champ is unbeatable, play that champ. Learn their kit, and you'll find it easier to counter them.
Ask people for help/advice in your games. You're going to get a lot of assholes, but just ignore them. Even some of the meanest people are eager to share their knowledge.
Practice practice practice! Then do some research, and practice some more!