Because your opponent can only place 2 stones each turn, she can't smother any group touching at least 3 empty spaces. So ensure your most important groups always touch least three empty spaces.
It's possible to create situations where a group has 3 or more empty spaces your opponent can't ever fill. This makes the group un-smotherable, a big advantage. The methods for achieving this are complicated and still poorly understood, but be on the lookout for opportunities to do this.
The board consists of concentric rings of hexagons. The the second-outermost ring is important, because groups with lots of stones on that ring are hard to capture without losing a lot of stones in the process. Therefore, in the game's opening phase, place most of your stones on that ring.
When you make a size-5 group, it can no longer evolve, which reduces your flexibility. Don't make a size-5 group unless what you gain from it is more valuable than the lost flexibility.
If your opponent has two size-5 groups of different colors that both touch the same empty space, she can't place a stone there without overgrowing and losing one of her groups. Therefore, if one of your groups is adjacent to that same space, your opponent can't smother it without overgrowing, giving you an advantage. Such empty spaces are called strong liberties. Try to force your opponent to make strong liberties for you, and avoid making strong liberties for them.
The size-4 pinwheel shape seems powerful. Try building it often.