My girlfriend is hot. I want her to dress sexy sometimes, but she stays pretty covered up....

She probably has respect for herself and you should respect her for that! If my man ever told me to dress more sexy I would leave him.

Positive reinforcement. Gush about something you like, something specific.

The #1 reason why a girl may stay covered up is because she believes she's fat. It doesn't matter whether this is true or blatantly false -- the reason is no less firm in her mind even if she's only 90 lbs.

If this is the case, do not address this reason, do not "knowingly nod", do not even acknowledge you know anything. This is key.

Now, focus on ONE thing you like about her physical person. Pick something you've heard her say she likes, or at least that you have not heard that she dislikes. Necks and shoulders are safe bets -- sensual and yet neutral -- or if you really wanna go for the gusto, breasts. If you're not sure, go for shoulders.

"Oh, honey, I just love how that shirt shows off your (part). You look so hot!" Then maybe growl and kiss her all over (part).

These statements not only express how sexy she is, but that her sexiness is tied in with HER CLOTHES. You can bet, once the message is reinforced enough times, she'll buy an item or two that will (tastefully) show off (part).

Note, be sure to keep on with the same part-choice!!! Otherwise, she'll see right through you.

Shop with her for something sexy - but not too sexy and then ask her to wear it when you're spending a night in together. she'll see how much you like it and with you as the only audience for her new style, she'll gain confidence and hopefully start adding a little more spice to her style.

Let her know how sexy you think she is. Give her the confidence to dress sexy, but if is not her style don't be too pushy.