* Don't use a locking death grip on the oar handle. Curl your fingers around your oar gently, and use the pads of your hands to pull an easy, even stroke.
* The blade of the oar should be the only part of the oar immersed. If your loom (straight, round part) is in the water, you're "burying your blade" and getting more resistance than you should. Your goal is to 'paddle' a little bit of water, not move the ocean with your stroke.
* During your stroke, lean back and put pressure on your feet. I equate this to a sort of "half-stand" without moving your butt from the thwart.
Second, line handling.
* Learn two knots: the rolling hitch and the sheet bend. The former is used to make the halyard fast to the yard (the wooden pole at the head of the sail) and the latter is used to make the sheet fast to the clew of the sail.
* Lines are almost always coiled on deck (not in your hand, like a cowboy) and go CLOCKWISE.
* "Ease" a line means to pay it out slowly. "Heave better" means take up a little more.
If you can master these basic skills, you'll be much more efficient. Remember, contrary to the skills of soldiers, the sailor is expected to be a skilled, thinking being - most of what you have to do, you do on your own initiative. The do not have such structured commands where we can specify "right hand grasp the small of the stock" etc.
I know it can seem overwhelming at first, but after a few times in the boat, it will become second nature, and we can move on to more complicated evolutions.
More on that when we're ready.