We generally 2% paraformaldhyde and get good signals.

Tween 20 and acetic acid/ Methanol (1v/3v) or 4% paraformaldhyde in PBS

We used 4% PFA in PBS with 0.1% Tx-100.

depends on what it is you want to look at.  i generally avoid organic stuff unless absolutely necessary.  fixation is typically done before staining and never after.  these are just my own experiences but it really depends.  microtubules are really hard but can be done with organics and FRESH NaBH4.