The main thing receivers should do is play to their strengths but be able to effectively build their game around their strengths.
Let’s say for example, you have great hands. A big focus of your game should be trying to put that on display. So what should you work on? You should work on your route running ability. Make it easier on yourself to make those catches. If you can create separation while having great hands, not a lot of people will be able to stop you.
Another example, if you are extremely quick and can get separation, I would say a big focus of your game should be developing your hands. This is for my smaller receivers. If you can develop your hands while always being able to create separation, you will be a force on the field. Like I said before that combo is very dangerous.
If you are on the bigger side, and let’s say you are average at pretty much everything, I personally would focus on improving your physicality. If you are decently sized and not physical you are wasting your potential. I would spend a lot of time in the weight room developing strength, explosiveness, and power.
All WRs have different strengths. But if you can design your game around those strengths, then you will win.