Find a local tailor, who knows what they're doing, and stick with them. A good tailor (not some hack at Men's Warehouse) can do wonders with poorly fitting garments.

At a minimum, a suit (which is essentially what this uniform is), will need sleeves altered and trousers hemmed. Don't forget to have your tailor move the stripes when they alter your sleeves (bottom stripe 2 inches from the bottom of the sleeve and 1/4 inch between stripes; same as the Navy). It's reimbursable and you'll look like a hack if the sleeve is simply chopped off.

For those who have forgotten, tailoring reimbursement amounts and procedures are in a new uniform FAQ on my.envoyair on the Flight page.