If you're buying in person or chatting with customer service, ask these:

• What's the return policy? Gifts sometimes need to go back. Know the window and condition requirements.
• How does the fit run? Does the brand's regular fit run slim or true? Is the oversized actually oversized or just relaxed?
• What's the fabric composition? If it's 100% cotton, it'll breathe well but might shrink. A cotton-poly blend resists wrinkles and shrinks less.
• Can I get measurements? Don't rely on S/M/L. Ask for the chest width and length in inches.

These questions work online too—most support teams will give you the numbers if you ask.