What type of haircut should I ask for if I...?

I am a male. I have not had my haircut in... well I do not know how long (less than a year ago). but I think my hair is too thick. I don't want the length to go away (a little bit shorter, would be fine). Basically it's gotten to the point where I barely wash my hair once a week, because it gets so frizzy and poof-y for DAYS after I take a shower, and by that time it just looks all greasy. So if I got my hair thinned out (A LOT) would it not get all frizzy and poof-y after I take a shower? I think I am gonna get it cut tomorrow. should I just ask the lady to thin the crap out of it?