It depends on what model you have.
In general, Epson print heads do best if you use them at least once a week. They don't like to sit.
The big advantage of most Epsons is that you can buy after-market cartridges for them and save large amounts of money.
For example, my vendor just had a 2-for-1 sale on new, after-market carts for the CX4800, and I got 16 carts for $36 delivered!
When carts are that cheap, you don't mind using your printer more, which is what keeps Epsons working.
The best way to clear the heads is to use the printer, preferably printing in highest resolution.
MacIntel Mini 1.83, 2 Gig, OSX 10.4.7; iBook G4 800, 640 Meg, OSX 10.3.9