I too am new at boating, but after taking the boat to the lake a sh!!t load this spring and summer gave me plenty of practice and learning what my boat and trailer like, I have a 17 ft javelin with just two bunks and a roller at the end of the trailer, I just kept experimenting with it at the ramp til I figured what depth the trailer needed to be to launch and load, I found that if i back the trailer in till the tires(single axle) are sticking out of water by about 3-6 inches of water and bunks are 3-4 feet out of water this gives me plenty of dry ramp to launch and load by myself with ease and without ever stepping into the water

But when your new to boating take my advice and be patient and be prepared to have a few guys laugh at ya while your in this learning phase, and when your at the bow gettin ready to step off onto the tongue to finish winching the boat onto the trailer, keep in mind the cables to the trolling motor like to REACH OUT AND GRAB YOUR ANKLES:D luckily I have good balance

And dont be toooo proud, if you dont know then ask someone who does, theres alot of good folks here and at the ramp that will help ya out