I always ship home after family holiday visits. I put most of the gifts in a large box and "pad" it with clothes.
The best way to do it if you think you'll only be shipping one way is to open an account with a shipping company, such as UPS or FedEx. With an account you don't have to know what the box weighs ahead of time, or pay in advance. (If you work for an understanding employer, you also may be able to use one of their account labels and reimburse the company when the bill comes.) Also, using an account is usually cheaper than the walk-up rate.
Put a pre-labeled flattened box at the bottom of your luggage, and bring a roll of easy-rip packing tape. You can leave the box at your hotel's business center or front desk on your departure date, and call for a pickup.
IME in recent years, FedEx ground tends to be cheaper than UPS. Go to their websites and estimate an imaginary sample package to find out. Pay strict attention to the shipper's limits on the size of a standard box -- oversize will cost you plenty.
If you can't use an account label, there is a Kinko's just north of the Crossroads shopping center, at 12181 S Apopka Vineland Rd.