The primary method I use for steaks is this -
First, it has to be a good steak, or no amount of proper cooking is going to make it anything but leathery lol. Good marbling (thin white streaks, not the thick bands of fat) and I prefer them thick.
I marinate them for a few hours, sometimes overnight because I forget they're in the fridge... heh, in olive oil with red pepper flakes, green onion, a clove or two of garlic - crushed, black pepper and other seasonings if I'm in the mood.
Then, either I put a little olive oil in a cast iron skillet, get it nice and hot and sear the outside of the steak, both sides and the edges too and the pop the whole pan into the oven and bake for 10 minutes or so to complete the cooking.
Or -
I get the hot skillet again with some olive oil, not quite as high heat and toss in the steak, giving it about 4-6 minutes per side without flipping it over more than once. The more you turn the steak over, the tougher it gets.
I touch the steak to determine done-ness - if it feels very soft, it's still raw. A little firm is medium rare, very firm is well done (overdone, imo lol). Finally managed to show my DH how to poke it for done-ness instead of cutting it in half in the pan! Gah! lol
Meat thermometers would work too, I suppose
but thats all. I don't like to add a lot to it, just a few simple spices to increase the flavour as I love the taste of the steak all by itself!