Colonize every inch
A perforated wall unit makes the most of the vertical space, allowing you to hang shelves, hooks and even see-through containers (for small objects such as twine scissors). What you need all the time should stay low and accessible; the less frequently used can go higher. With everything up on the wall, you'll have plenty of countertop to spread out on.
Make it comfortable
Durable metal benches mean you can sit while you work (and they double as stepladders), while inexpensive light clips provide spot illumination. A very un-garagelike chair is a nice perch when you're taking a break.
Tool bag (with three tools) $59, Gardening tools $17 to $59 each, Brown gloves $39/pair, Potting soil $6/bag, and Pots $6 and $12 each, all at smithandhawken.com for stores