Particular Lighting Technique?

does anyone have any tips / tricks on how to get more of a greyish look to photos using lighting?? I really only have my flash unfortunatly, but I'm trying to achieve a blue'ish greyish look (indoors) with a fetish model...

A gel on the flash can give you pretty much any color hue you want, and they're pretty inexpensive (or even free at times as part of promotions!). Or are you looking for a way to do it with equipment you already have and stuff you might have around the house?

You could also do a lot of that sort of thing in post-processing, playing with color parameters to adjust to your liking.

In addition to the good advice above can also adjust your cameras white balance setting. In your menu you can set color temp. to whatever temp want (within its' range of course).

Or you can experiment with choosing one of the other pre-set WB settings to see get closer to the creative effect you want. I'd also suggest shooting RAW so you have more latitude in post processing to make additional adjustments to WB.