I'd say not to emprove too much skills that you won't use at ~5x-60+ because as you know most of spells change and than you have to start from the begin with skill emprove. I'd say check which skills you'll keep and which you won't use anymore, and emprove only the ones you'll use even after 60.
Donno on what you usually put your emprove points, but I think best thing to do is to put them at cooldown, gonna be useful
