Form fitting shirt?

Form fitting shirt?

I have a few black unisex t-shirts I wear for work that are waaay too big for me, and they're smalls! I'm kinda petite and I'm lost in them because they're so big. I've already gotten my manager's okay for this; how would I go about just bringing them in a bit so they fit me better? I want them to be a little more form fitting, especially around my waist and fit me so I don't look like I'm wearing a pillow case. I don't own a sewing machine; would I need one? I can sew by hand. any tips?
Persimmons

Persimmons

Seedling ID, aloe vera Qs

Seedling ID, aloe vera Qs

Stylish Bargains.

Stylish Bargains.

NEW DORM – REARRANGED

NEW DORM – REARRANGED

Veggies!

Veggies!

How quickly things turn!

How quickly things turn!