It would be adviseable NOT to paint your counter tops. A two component epoxy (rated for incidental food contact) is the only thing that would be strong enough to stand up to counter use - and even then it isn't as strong as formica. Also, the price of 2 comp epoxy - combined with what it takes to prep and apply - you could go to THD and buy something already made (assuming you have straight counters) for likely less than the paint would cost.
Please don't try and use a wall paint on the counters - they are not designed for this sort of use and will fail.