Tips and tricks for growing veggies in small outdoor spaces

Take advantage of vertical space. I see a lot of pallets repurposed for smaller planting areas.

Place plants in the proper conditions (i.e., determine if it is full sun, part shade, etc.).
Use the largest pots you can afford (those fabric pots look affordable but they do dry out quickly, so if you travel, plan accordingly).
Use good quality potting mixes--check garden centers for bulk orders.
Check seed companies for varieties that are adapted for small spaces.
Make use of trellises, etc.