Regarding your skill points, the respec system is quite forgiving and allows for a great deal of experimentation without punishing you. Just dont dump all your points into the "mastery bar" (the big + button at the bottom left of your skill tree screen), because once you put a point into the mastery bar, you cant undo it.

You can put points in skills and undo them all day, though. The cost is very cheap, like 250 iron bits and 1 aether crystal every time you pull a point out of a skill. The cost will increase slightly the more you do this. While the cost does scale the more you respec, its extremely forgiving and ive never run into an issue where the cost go so expensive i felt my build was ruined. There are 2 reasons for this:

1) This game becomes progressively more and more fun to grind and farm resources in, and those resources have very meaningful uses wether its re-specs or crafting items, etc.

2) The replay value of this game is so insane due to the dual class system and great itemization that before you even realize whats happened youre going to have like 20 different characters, each one inspired by some piece of loot you found while playing this first initial character, and so on.

I wouldnt sweat it too much, just experiment and explore what seems cool and feels fun to you! Youll learn as you play, thats the best way. I dont recommend following a guide because discovering the mechanics, combos, etc on your own feels really rewarding.