Good luck to you on achieving your goals.
My goal when I started was just to be able to consitantly shoot 270 on a 30 target course(no 12's or 11's) in the hunter class.I reached that then my goal was to consistantly be able to shoot 280 on the same course consistantly in the open class then I achieved that.Then the 11's and 12's came into play and my goal was to shoot around even and then I achieved that.
I had changed my goal to shooting up on all courses that would allow but as soon as I started shooting more up scores,I got really burnt out on it and just started playing ball with my kids instead of going to the shoots.Now I would be lucky to shoot a 280 from the mbr class and counting 11's.[&:]
Just ponting out is a great idea to set achievable goals,maybe even challenge yourself a bit more than I did.Just get the proper instruction early so you don't have the learning pains I did.
One of my favorite yardage practices is to take some small orange cones and place them at 5 yard increments to your target while shooting.This will teach you what 5 yards looks like all the time from different distances.Then,try judging to the targets with the cones and try and break it down into 1 yard increments so you can see what 34 looks like opposed to 37.
Another which hs been mentioned is the halway technique.Judge halfway and double.
Get a rangfinder,go to the woods and fields and start judging.Judge anything and everything to get better.
IMO,the most important is to shoot as many targets as possible and learn what they look like from many different distances.Being able to walk a 3-d course with your rangefinder and judging to the target can be most valuable in learning to judge targets.Too many times the ground just isn't visible and you need to know what they look like from different distances,then you will find yourself using that skill more and more when the ground is visible.