It's nowhere near the amount of help I
want to give you, but providing you with my SK Mathematica notebook just doesn't feel like it would be appropriate. In the end, the real decision rules will be based on your character's intended playstyle. Your mileage will vary if you take any one person's overly-simplified advice. In light of the general boundaries on what can and cannot be freely shared, my most emphasized suggestion is to do some of your own testing.
One poorly-documented piece of forum knowledge I
think I can highlight is that training a resource such as mana or hitpoints directly will give you more resource bang-for-buck than other stats that may contribute to the pool, both in terms of raw increase and the regeneration bonuses you get for it. Of course, you still need to ask, is that effective? That answer depends on the environment you expect to encounter. What are you gaining? What are the opportunity costs? How often have you found yourself wanting either in the past? All things to ask.
Some players will say only one mechanical approach is best. Such likelihood maximization might be of interest to you if you agree with the assumptions involved.
The best way to claw your way out of newbie status in any environment is to ask questions, think critically, and test often.