Lots of good info on this site.
If you can't start with a fairly heavily planted tank, see if you can put in some floaters, or even house plant cuttings (not submerged, just dipped into the tank). Plants that are exposed to the atmosphere (cuttings, floaters, emergent growth, etc.) has much more access to light and CO2, and can do a better job of taking up excess nitrogen and such. It's better if you can get the tank full of plants from the start, that way there are less niches for algae to exploit.
For future tanks, there isn't really any need to cap flourite, it works fine by itself as a substrate, or it can be used as a cap for dirt/MTS.