3 coats of a good epoxy primer.
If you were to search other forums you'd find strong support for PPG and Southern Polyurethane Inc. or...SPI
For the price it's hard to beat SPI.
If your worried about 'durability' watch
this test made by some guy on youtube who wanted to decide for his own peace of mind.
I'm still waiting to see someone do a head to head test of PPG and SPI.
