Dina - I think maybe the shaving idea is not a recommended one! My friend does it and when she 'forgets' the hair on her upper lip becomes quite noticeable. Also, y'know when you haven't seen someone for a long time and you get a hug and a kiss from them? Well, her mouststache prickles a little.
Shaving doesn't cause the hair to get thicker or darker, but apparently according to a little research I did, the razor will "cut off the fine tip of the hair. When this happens the hair appears to be thicker and darker, but in reality it’s just got a flat tip on it. This gives it a thicker, fuller appearance."
You'd be better sticking to bleaching or waxing - or save up for electrolysis for permanent hair removal.
The things we women have to contend with!