There's a bunch of hard-skills (you mentioned some) which you will gain naturally as you play more poker. Specific plays, situations that always play out in certain ways, etc. But there are also a lot of soft skills which it's harder to figure out. (Note, I assume No-limit Texas Holdem below in concrete examples, but this applies to all versions of poker).
Never make an action (other than folding preflop) without thinking for some minimum number of seconds. Pick a number that's comfortable for you. Not only does this help prevent bad snap-decisions (when you're starting, things like "oops, there was 4 to a flush on that board!"), but it helps balance the times where you actually have to think, giving your opponent less information.
Think about how a decision will look if you described it honestly to a friend in an hour. Can you back up your play, even if it fails? For example: you're considering making a big bluff because you think he's weak. Why do you think he's weak? If it's a hunch, really try to work out what is driving the hunch. If you make the bluff and he has a big hand, there's a chance it was still a good bluff, considering what he may have played similarly given the situation.
Slow down even when you're nearly sure you're winning. Not for fear of losing, but to evaluate how you can make the most out of the situation. Is he willing to pay off your nut flush with his cards? If not, how much is he willing to pay? Will he misread an awkward all-in as a bluff and call, where he would have folded to a smaller bet?
Be willing to completely re-evaluate. Start by predicting what your opponent is going to do. If he differs wildly, don't try to fit his action into your previous mental-model. Throw away the model, keep the facts, and start thinking again. It's more important to correctly fold/call against the $150 river shove than it is to think "last time he bet $10 on the flop and he was weak, so he must be weak now". People hit inside straights, people river sets, and people make moves on the flop in multi-way pots that seem random or inconsistent because they are using their strategy, their reads, and their history.