Well, I've tried doing both, but I find skipping gears much harder, because you have to be extremely precise with RPM matching, otherwise you are going to lock the driven wheels. So whatever works best for you
As for me, i'm far from being a pro, I myselft started heel-n-toeing only a short while ago, but it has its benefits. Also, you can first practise it without actually braking. Go to ky-oval, and drive at some constant speed, and try to shift up and down without jerking the car. F button hels a lot
Say @80 km/h you should be shifting between 2nd and 3rd.