There are many factors involved with the gaining of skill percentage points. Here are some tips:
Get premium time - it provides a boost to the chance to get a skillup.
Happy Hour - it doubles the premium time chance boost for an hour each day.
Ensure you are using the latest skill in the tree that you have unlocked.
If skillups are slow, switch between trees. For example if you find feeder fishing has dried up, move to float or spin fishing.
If working on fishing skills ensure you are going after a variety of fish that you can catch very quickly. For example, fishing for baitfish on winding rivulet can help as the bite rate is good and you catch a variety of species
However, please remember there is a certain amount of randomness in this as well, and some days you are simply unlucky. Dry spells do occur from time to time.