I need to grease the hubs on my '93 trailer, the trailer has instructions on what to do, My qst is there anything else I need to know before I do this and what type of grease is the best?

I have the hubs that require you to pry off the metal cover and it is a single axle.

This seems like it is simple to do but I dont want to screw anything up, as I have a tendency to screw it up!!!

Thanks for any tips you can give me on this!!!