I'm not a guy but I'm pretty damn opinionated when it comes to style...
Jeans- Not too tight, not baggy unless it's on purpose, and if your ass crack shows when you are sitting down, you need to find a new style.
Personally I dig long-sleeved fitted tees, that are cut for a woman and made of a nice material. 100% polyseter is NOT gonna cut it, lol... natural fibres!!!! The material should be dictated by where you are going... like, cotton for whenever, and something expensive like thin Merino or silk for the evening.
I think good accessories can add SUPER sexiness to this basic outfit... big ass hoops, stilettos, a badass belt buckle, matching bag... and of course your attitude!!!
IMHO too much skin/ass crack/cleavage/etc just looks like you're trying too hard.

Oh... I think long sleeves, and jeans that are like an inch too long unless you are wearing heels, make you look taller and thinner overall, and give a cleaner sihouette.