My strategy varies from the above, though it may change if they implement one of the things being talked about.
I push taxation up to 100%, spending to 100%, cut social to about 15-20% and leave the other two sliders balanced, so 40 research, 40 military. I leave taxes at 100% till morale gets below 50% on my homeworld and adjust taxes a little down, then wait for below 50% morale again. The point of all of this is to expand, expand, expand. Homeworld is building only colony ships to start with. I also rush build them once they've been pushed past the 50% complete mark, assuming I have the funds (thus why the 100% taxes!).
I do this till there are no more planets within my ever expanding range to colonize. Then I'll reverse social spending and military spending.
My homeworld is generally queued to build 2-3 factories, then 2-3 labs, then morale, economy or whatever else happens to be researched. Extra space I will fill evenly with factories and labs.
New planets are always, factory, starport, lab, factory, lab, morale, embassy then whatever I decide to customize that world with. I tailor some worlds to be my research worlds, others industrial, and yet others economy. The only exception to this are worlds on the edge of another empire, which I will build several embassies upon. I've been known to build solid embassies on class 4 planets

Gotta push that influence...
Also, once I have run out of room to expand, that is when I start to build a military, if I have the technology, which presumably I do by then.