It is better to learn why you play specific hands and why you don't play specific other hands.
Hands have some important properties
1) Hand strength -
odds of winning at showdown unimproved big pocket pairs and big Ace hands
2) Hand potential - odds of becoming a strong hand - set or better.
3) Domination and reverse implied odds - if you hit a good hand - top pair, what are the chances someone also has top pair and a better kicker.
4) Blocker value - holding certain cards reduce the combination of strong hands that can either 4bet or call you, so you can use them for 3betting.
5) Board coverage - this is more advanced, but if you lack certain cards in your range than villain can
bluff you on boards that miss your range - for instance if your early position range lacks low cards.
So we aren't openning certain hands in early position due to the high chance of a dominating hand calling us.
We are 3betting with hands either for value (big pocket pairs) to get called by hands we dominate (we hold AK and they call with AQ, AJ, or KQ, or a variety of suited Ax hands), or to fold out hands that dominate us, or hands with blockers that prevent them holding strong hands (AK blocks 3 combos of AA, and 3 combos of KK, so they are less likely to 4bet). Our 3bet bluffs often come from the hands that are at the bottom of their openning range because it will fold out the worst hands in that openning range that dominate the hand we are 3bet
bluffing with.
We are openning more hands in later position because there are reduced odds of someone having a strong hand, and we are more likely to be 'in position' and the most likely callers (BB, SB) are likely to be 'out of position' and we have better odds of stealing the blinds and antes.
We have some small pocket pairs, or mid suited connectors, or A5s/A4s/A3s/A2s in our early and middle position opening ranges to improve board coverage.
