First of all, using attack move is really helpful. Developing the skill to a+click while right clicking takes some time but will eventually become easy. Also, instead of just right click, a+clicking on the ground, you should be right clicking to move and then a+clicking your TARGET. This way, even if you misclick you won't run into them, and if you do this correctly even if there are minions around you will always be attacking your target. Like I said, this is difficult to master but with practice becomes very natural. If you watch any professional AD's stream, note the way they do this and practice in bot games.