I believe that you really have to understand the dynamics of the effects of wind & current on the boat & propwash / propwalk before you can effectively dock a boat with confidence (and minimal damage!) Believe me, and I speak with experience, that trial and error is not the way to go. There will be variables such as wind direction and strength or current that will always affect the boat during a docking maneuver. Only with a complete understanding of the dynamics, will you be able to understand what is occurring and adjust accordingly along the way. Also, going into a docking situation, you have to anticipate what is going to happen and know what to do before things get out of control.
I would start by reading Chapman's & Annapolis Book of Seamanship chapters on docking. Also, Nautic Ed has an online docking course with self tests that will challenge you.
Get someone to help you aboard. Walk them through your docking plan and show them specifically what lines you are going to use, where to tie off, and the sequence. It is great to get help on the dock; however, there are a lot of people who have good intentions with only rudimentary knowledge & skills who can mess up things for you.
Always have an abort plan in mind just in case things don't go according to plan. No harm in aborting and trying again, rather than forcing a situation and losing control.
Finally, as everone has emphasized, practice----there is no substitute for experience. Hope this helps a bit.