Color management is the 800 lb. gorilla of digital printing. In a nutshell, you need to
1) Make sure your monitor is calibrated so you know what you're seeing on screen
2) Have accurate profiles for the papers/inkset you're using. Use application managed color with the correct profile and paper settings chosen in the printer driver. If colors are still not accurate, either you've messed up one of the settings, or your profile isn't very good. Halfway decent profiles should get you at least pretty close, and a simple adjustment layer in Photoshop will take care of the rest. Don't try using the adjustments in the printer driver, because there's no accurate preview and often this will cause the printer to take over color management from the profile and/or Photoshop.
3) RIP's are useful mostly for high productivity printing, placing multiple images on each sheet, or getting access to superaccurate profiles. They are accordingly pricey. You may want to start out learning to use a basic workflow with profiles before learning to use Epson's RIP, which from what I've read is mediocre.
