It would help to know what kind of boat, length etc...
Yeah, the type of boat and trailer makes a huge difference. My boat is a 12'semi V. Once everything is ready I back the trailer in until the back of the boat starts to float up. Depending on the angle of ramp, I might back in further but never far enough that the truck tires are in the water to the rim. Then I loop the bow rope to the trailer and push the boat off. Then I grab the rope and tie the boat to the dock, or beach it and tie it to a tree. When it is time to load up, I back the trailer in so the bunks are partially submerged. Again the amount depends on the ramp. Now I take to beached boat and push it out and pull it back by the bow rope and get it on the bunks. Then I get on the tongue and pull the winch strap to the bow eye and crank it on.
Now, my father in law has a 16' deep V with a 100hp Johnson, on a really nice shorelander trailer with roller bunks. All you have to do is back it in until the stern floats, back it off and dock it. To load it, just back the trailer in so that most of the bunks are under and drive it on and hook up the winch strap.
Don't forget to unplug your lights before backing into the water!
Also, do a search on this site as well as you tube on launching and loading boats. You will find a lot of what not to do.