How to ask for a raise?

It's just been over a year, and my next pay chance is still the same pay as usual. The company policy says they will review a new employee after a year for raise. I am not sure if I should ask for one just right after a year. Is it too rush? and I know this boss might forget or even play dumb to avoid it. Ques: How do i approach this? Is it okay to email him a letter for a raise? And how should i bring it up again if he doesn't respond me afterwards?