Hm, well mod wasn't neccesarily bell-bottoms and headbands, but it's all a big part of the 60s conglomerate look.
For makeup, I'd say Twiggy is the most recognizable face of the mod look, the graphic eyes and fleshy, toned down mouth. False eyelashes both on the upper and lower lashlines, along with a very defined high crease for the lid is good. Something light and shimmery across the moveable lid and below the brow, and then you know where you feel your actual
brow
bone? That's as high as you want to go for your ultra-defined crease. I'd use blacks and whites, or neutrals for this for this.
http://www.virginmedia.com/images/1twiggy-431.jpg
That photo is a pretty good example of what I mean with the crease. It's very heavy, high, and defined. I don't think I did a good job explaining, haha. Lips, just go with a frosty light pink or a fleshy beige nude. I don't think blush was very popular for the mod ladies, just seems like light contouring and maybe a touch of bronzer.
As for hair, the bob was a popular cut I think, but if you don't already have a similar cut, I think a headband would definitely show what decade you were representing. So would bell-bottoms, if you can't wear a Mondrian print dress at work. :0)
I hope that helps, good luck!
p.s., for some more visual representations, I get inspiration from watching
Scopitones, which weren't neccesarily all mod either, but it's a good way of seeing what popular looks were done in the 60s. If you have blunt bangs, you're in the money in terms of that era's hairstyles. All in all, the biggest thing I'd say is false eyelashes and a toned down mouth. Nothing was very bright on the face, it was a more "supernatural" look. I spent five paragraphs just telling you that over and over, and I'm sorry.
