What is your general style, and what kind of shirts do you normally like to wear?
Definitely a couple ways to style these, like @ler mentioned you could do a baggy or cropped tee, or you could also try an oversized short-sleeve button-up with a graphic print like these examples from Valentino or Prada (there are definitely cheaper options available from eg. Zara, or you could scope a thrift store and I'm sure you'll find something). Could also try a simple white tank for a slim top/chunky bottom type of look.
As far as colors go, here's a color chart that I think outlines some great combos with olive. I especially like how olive pairs with gold or cream, or with a blush/coral type of color. Some teals work well with olive too.
Just my 2 cents!