The concept is simple, this is the QUICKEST way to erase strokes from your score.
Work on upshots
Work on short throws of 150 feet or less. Go through all scenarios- headwinds, tailwinds, straight shots, right turning, left turning, and anything else you can imagine. Get a stack of mids or putters (stop using drivers for these shots!) and drill this distance.
Practice Games to help you improve quicker
Putter only round
Yes, it is self explanatory. Take your favorite putter to your favorite course. Throw that thing for every single shot. Drives, approaches and obviously for putts. You will be amazed at your score. If I had to guess, it probably won't be too much worse than if you had all your discs available. Why does this help you ask? A couple of reasons. First, you are getting lots of practice gripping and throwing your putter. Becoming more acquainted with your discs and understanding how they fly is very important. Second, your putter is your slowest, most accurate disc. Likewise, it won't hide mistakes. Upon releasing your upshot only to see that it is shanking 50 feet right of the basket, you won't be rescued by your putter fading hard at the end of its flight. Putters generally go where you tell them. Practice throwing accurately.
You get to play another practice round and are allowed to take your putter and ONE mid-range disc. You may use either at your discretion. You can shoot and score using just two discs. You will be forced to make accurate shots. You'll also soon discover that mids and putters stay on the fairway much easier than a maximum weight, very overstable, high speed driver. This is HUGE! Stay on the fairway. Much of disc golf is the mental strategy, and learning to confidently throw mids and putters will allow your mind to make the smart choice over the fancy one. A 150 ft shot lying in the middle of the fairway is much better than a 250 ft shot that hooked 60 ft into the rough.
You got the idea. Add ONE driver to the mix. Limiting your choices makes the game a lot more simple. Of course having other discs is very valuable and I'm not discouraging carrying lots of discs. The lesson I hope you can take away from these practice rounds is that you will feel completely confident with three discs in your bag to make the shots you have to make.
Hit the Brakes
As you build your confidence with your putters and mid-range discs, you should gain the ability to SLOW DOWN! Always throw your SLOWEST disc that can reach the target. Let's say you can accurately throw your putter 230 ft. When you walk up to that thrilling ace run on Hole #6 that is 212 ft away, put down your maximum distance driver, PUT DOWN your mid-range, THROW YOUR PUTTER!!! Don't be afraid to tee off with your trusty putter. The same concept applies to your mids: if you can throw your mids up to 300 ft, you really should be pulling those out for shots under 300 ft. I love throwing big drives just as much as the next guy, but if you want to see your score improving, put down your distance drivers on shorter holes and THROW SLOW!