First congratulations on entering the hunting arena. Sounds like you are already well on your way to where you want to be.

Don't know of any books, others might, so I will just tell you what has worked for me.

1) Does the gun feel comfortable, not too long or short? If not, figure out which and figure out a solution

2) Trigger contol. This has several areas to consider. I only shoot rifles that have had trigger jobs to eliminate trigger "creep' and lower the amout of pressure to get the gun to fire. Usually 2.5-3 lbs of pull is good. I spent my youth yanking on triggers that had creep and were 6-8 lbs. By the time they go off, you are so anticipating the shot that it is very hard to be accurate. Next, only pull on the tigger when the crosshairs are approaching the bullseye. No matter how steady you are, the crosshairs will wiggle. Make a conscious effort to only tignten on the trigger when the crosshairs are wiggling toward the bull. Sounds hard, but you can really do it if you concentrate.

3) Be sure the gun and bullet are accurate. For this, I usually shoot 100 yard groups with a gun vise. Be sure the gun can shoot at least 1-1/2" groups. Sometimes just changing ammo will tighten groups. On one of my guns, I had to float the barrel before it started driving tacks.

4) Are your recoil shy at the range? I am. On one gun, I had a recoil arrestor put on it and I immediately tightened up my groups. However, these things should only be shot with hearing protection because the do damage your hearing. Another gun I put a Limbsaver recoil pad on and that tremendously reduces the felt recoil. If you are recoil shy at all on your 300, you may want to try this.

5) Practice. And not just at the range. Dry fire the gun at home. Some people put a penny balanced on the end of the barrel. They dry fire the rifle and try to get the penney to still be there after firing.

These are the main points, I will try and think of more. However, managing recoil and trigger control have done more for my accuracy than all others combined.