When I had my first boat (make that my first several boats), recreational radar was in its relative infancy. Lots of power and room were required for a display for which the user had to bury his face in a mask. Fast forward, and my first radar was relatively low power, but was great for navigation through triangulation (way before Loran -- RDF was the second best way to triangulate), and possible collision avoidance).
Although I don't have any formal radar training, I have learned that there are basically two problems with radar: 1) echos that aren't really there, generally resulting from "side lobe" radiation, and 2) echos that are missing. Depending on the quality of your radar, IME, radar has advanced to the point that the risks of 1 and 2 are greater than with naked eyes. My suggestion is that, especially for collision avoidance, you run your radar 24/7 and find a target on radar, then determine if it is visible to the naked eye. If not, get out your binos. And conversely, find a faint target with your eyes and see if your radar is picking it up. On my boat, I have more confidence with my 25kw Furuno than with my naked eyes. Interestingly, it is mounted a little lower than my 6kw Furuno, but outperforms it at up to 6 nm. Ironically, choppy seas get a bigger reflection on the higher-mounted 6kw than on the 25.
As far as advanced topics like birds, I suggest you master "real" targets first. On my radars at least, to see birds I must turn the gain way up, and the pulse down. Unfortunately, that means lots of clutter (and the clutter control off). Still, with time, you will see birds with a decent degree of confidence from 3+nm off.