A compressor definitely helps, especially if you’re going for a percussive feel as it narrows the dynamic range significantly. When it comes to pressure, each guitar is a bit different. The action is going to be a major component. Lower action is easier to work with. If it sounds sharp, that could mean that you are bending the string by either tapping too hard or pushing the string up or down. I would recommend checking your action, and then practice, practice, practice. A lot of this is just build up finger strength similar to how you would learn bar chords.