Need some opinions :)

I used to feel like it was a waste training skills past 99 because I wanted to max out ASAP, and I still want to max out, but I figured out it was best to train skills past 99 if you feel like it.
Basically I train a skill when I feel like it, and I don't pay attention to if it is 99 or not, which leads me to training both sets. I find it very fun to have lots of option.

I think this is the best way to play, not to force yourself to do anything, which for a lot of people becomes frustrating and than they lose motivation. So basically, train whatever the heck you want to!