Many archers make the mistake of whacking away at a target that is the same distance as their comfort level. THAT'S WHY IT'S YOUR COMFORT LEVEL!! You never push yourselves.
Find, or build yourself, a range that will allow you to shoot safely out to 70 yards. Yes, I said 70 YARDS. (100 would be better) Start working your way out to that distance. It may take months, but I GUARANTEE that your shooting will improve so much that you will be amazed. I once shot 28 days straight and never got closer than the 40 yard line. On the 29th day I shot my first 20 yard 300 game in my life. My previous best score was a 289. You can shoot 300s at 20 yards and be a crappy distance archer. I have two friends that were examples of this until recently. I could kill them at 50 yards, but not at 20. It's all mental. I wasn't scared of 50, they were. Once they became comfortable their short range game improved and so did their long range shooting. Now I'm getting beat again.
Once you are out to 70 yards and shooting "archers M.O.A." (1" groups per 10 yards) start changing things up. Shoot off of one knee, shoot off of both knees, shoot while leaning around cover, shoot from your blind, shoot from your treestand, shoot...shoot...shoot. Make it tough. Now do all of this out to 70 yards. YOU CAN DO IT. If I can do it, anyone can.
Now, add some surprise one shot practice to your training regiment. If you are going out to mow the lawn. Grab your bow and fire ONE arrow at your target from your knees. Do it just like you hunt. Do this as much as you can. It will build your confidence and train you to make the first shot COUNT. Do this out to 70 yards too.
Now, do all the above with broadheads. Buy 6 of your favorite broadheads and use them as target heads. Don't screw with the dull practice heads. Train yourself to respect the sharp ones and you're less likely to get hurt in the field. Shoot those heads out to 70 yards...don't be afraid.
By pushing yourself to greater distances you will do a couple things. First, you will fine tune the archer. If you have a form flaw at 20 yards you can only imagine what it will look like at 50 and 70.
Second, it will force you to fine tune your bow. That little arrow waggle that you allow at 20 yards?? imagine what happens at 50 and 70. Fine tune those broadheads. A group that is off from your field points at 20 will really show up at 50.
Push your limits and your bows limits and both will become a fine tuned killing machine. Be timid at 20 and you will always be timid at 20. Imagine what a SLAM DUNK SHOT that 18 yard deer will be after you've been squinting at tennis balls from 70 all summer.
I don't advocate shooting deer from beyond anyone's confort distance. Practicing WELL BEYOND that distance will only make you MORE comfortable at your "ethical" limit.
Do it for the best reason of all....
FUN Shooting at big distances is fun. Forget the cost of arrows and broadheads, just build a bigger backstop