Easiest way is religion. If you beeline certain techs you'll be able to select your choice of religious benefits. Also, consider building Stonehenge... it alone will allow you to forego making shrines in all your cities (or do both for really fast generation). Make sure and get your 2nd great prophet to enhance your religion before you spend faith on other stuff.
Second is luxury resources... don't settle where you don't have at least one resource. Stay friendly with as many other civs as possible, and trade out resources. (And staying friendly can be difficult... you can't backstab, you can't eliminate other civs, you can't take city states, etc.)
Third are buildings such as colosseum, theatre and stadium. But those generally are spread out along the tech tree.
Fourth are social policies... but they are few and far between (as far as getting happiness goes).
Fifth are mercantile city states, as Dr. D said.
Sixth are some wonders.