Ok... The Mal thread...

[Tyr]

The single most important skill to learn in this game is last hitting. It's exactly what it sounds like, getting the last hit on minions as they die. You get gold off minion deaths only if you last hit, and it adds up.

It's ok to auto attack if the minions are near your tower, to keep them out of tower range, but usually you just want to focus on last hitting. Last hitting takes a bit of practice to know exactly when you need to hit the minions, but once you get better at it, you'll be buying items way faster, thus able to do more quickly.

Another skill to work on would be map awareness. Basically, try to be aware of where you think the enemies are at all times just by glancing at the mini map every now and then. If you don't see all 5 (4 if they have a jungler), try to quickly figure out where the missing ones went. If you are pushed out away from your towers and there are some people mia, unless you just saw them on the other side of the map, expect them to be coming for you.

Those two skills are by FAR the most important ones to work on. Creep score is a great judge of how you are doing on last hits. How often you got ganked for being out of position will let you know how you are doing as far as map awareness goes.

To add to that, last hitting usually means you ONLY last hit when it's not going to get auto-attacked by anything other than minions (like towers, like Tryg said). This way you're making sure the creep line is either pushed in your favor (it's much more favorable to be pushed to your tower than it is pushing them to their tower) or that the lane stays in the middle, which means you can get more last hits.

It's confusing at first, but once you get it down it's a nice little meta game each match.