You're going to get a lot of advice and instructions on this Jim. I've been loading my Trackers for 15 years now, and I almost always fish alone. So, I don't have the luxury of someone in the truck waiting for me. Pure and simple, I just back the trailer in until the step pads on the front of the rear fenders are just under or almost under the water. Then I approach in idle and if it looks good, I increase to a high idle as I hit the trailer, and without waiting for the boat to stop, I push up the throttle to run it either completely into the roller or, just short of it. After all, with Trackers, you really aren't dealing with a ton of boat and winching it up to the roller is pretty easy. By bringing the trailer that far up the ramp to start with (at least most ramps) I can just step over the bow and drop down onto dry ground and hook the strap and winch it tight. The real bears are those very shallow ramps, and some of those leave you no option except wet feet. You'll hear more techniques, so take your pick and try them out.
Jack