I mount tv's for a living. There's no worry of hitting wires as long as you're going into a stud. In fact, where your outlets are are a good indicator of where you have a stud as the boxes are normally attached to one.

You should be more worried about hitting your water pipes, but it's easy enough to avoid those, just don't drill into the wall where there's a bathroom directly behind it.

If you want to ensure that your stud finder is good, get a long thin piece of metal and poke it into your wall (assuming it's not wood panels) and if you get resistance early on, you've got a stud.

If you want to ensure you get it exactly where you want it the first time with no extra holes, mark off exactly where you want the bottom of the TV on the wall. Then measure the heighth of the TV. Place the brackets on the TV, along with the wall bracket and then measure from the bottom of the TV to the top holes of the wall bracket. Use your TV height measurement to ensure the TV is at a good angle (honestly, I see so many people fall in the trap of placing it high up, neglecting that you'll have to crane your neck to watch it.) And then use the "drop" (the bottom of the TV to the wall bracket hole) to mark off where your bracket should go on the appropriate stud

Place the wall bracket on the wall where you come in contact with two studs and drill your holes, and then screw in your lags. And that's the hard stuff done.