In general, when you're talking about the mid-stages there are a few guidelines:
1. Steal blinds whenever you get a chance.
2. Be okay flatting with suited connectors, broad-way cards(anything that flops well) when getting a good price (provided you're not in a desperate stack zone).
3. Don't ever think of set-mining unless you're in a table full of big stacks.
4. Adjust your short-stack strategy because antes have kicked in and your range needs to be adjusted.
5. If you've been observant enough, you might have some reads on opponent (these reads are valid if you've more than 70-80 hands on the villain, else don't bother). Use them and wisely.