Definitely look at the techniques suggested, but here are a few basics off the top of my head:
-Get your RIGHT elbow UP - parallel to the ground. This creates a pocket for your rifle butt.
-Get your left elbow into the side of your ribcage. This gives you support.
-The trigger should be to the left of the first joint on your trigger finger.
-Without a round in the chamber - Stand sideways to your target - left foot in front...close your eyes. Put the rifle up to your cheek and aim with your eyes closed. If you are not close to being on-target, adjust your feet, do it again and practice this stance until you naturally point your whole body at the target.
-Maintain a consistent sight picture. The front sight, rear sight and target should always look the same to you. Otherwise all your other improvements mean nothing.
-Aim at your target and hold your breath.
-The sights will always sway around the target. Decide for yourself when the amount of sway is acceptable. Your shot will land somewhere in this range. If it's not acceptable, relax, take a deep breath and set up again.
-When the sway is acceptable, s-q-u-e-e-z-e the trigger so it surprises you when it goes off.
-FOLLOW THROUGH - Maintain your sight picture through the shot.
-CALL your shot to yourself before it's marked. "High Right"..."Low"...etc.
-Check your shooting on each shot, not just the group. Use a spotting scope, binoculars, rifle scope or telescope. You will only improve as a rifleman if you measure yourself on every single shot.
-Your objective is to keep every fiber of your body still except for the few trigger finger muscles involved in pulling a few pounds of trigger.
-Just like a big league pitcher or at the free-throw line...get into a cadence. The difference is, this cadence involves a lot more gear and the adjustments are MUCH more small and precise. Have your range bag, clothing, ammo, gun, sights, etc. set up the same way every time. Get rid of anything you don't need up at the shooting line.
Gear:
-A sling will not really help you shoot standing up. (Well-- maybe a Ching Sling can, but I have no experience with one). But it is invaluable for shooting prone, sitting and for carrying your rifle. Start with a simple cotton green US military sling and learn how to use it correctly. You will probably have to add wider sling swivels to make it work on your Ruger.
-Wear a thick glove on your left hand. Even a thick ski glove will work. Something with a good grip and to insulate the rifle from your body.
-Wear a sweatshirt and a leather or canvas jacket. Again - something with a good grip and to insulate the rifle from your body.
-When you're ready to move up, spend some bucks on a nice shooting coat. But they are not at all necessary to start.
-Wear a good pair of boots.
-Wear long pants and long sleeves to keep the sun, bugs and neighbor's stray brass from bothering you.
-I always have problems with hats and sweating, but a baseball or boonie hat will keep the sun off your eyes and the hot brass off your skull.
-Ear and eye protection.
-SHOOT SAFELY!