When assessing a space I always take photos from every angle, try to picture the space fully grown, and imagine myself in the landscape. It never hurts to make some quick sketches too- even if drawing isn't your thing. It's helpful to know about how tall plants will get if you plan to have full-sun crops nearby or plan on having seating around the area.
Step 1: Define the spaces that are to be planted. Although the hardscape (brick, stone, or wooden borders) is the negative space, when executed with style it brings the entire space to life.
Step 2: Remove weeds from areas and apply a thick layer of compost. Remember: Even drought tolerant plants benefit from compost.
Step 3: Research before planting to avoid rookie mistakes like an invasive species takeover, crowded and overgrown beds, or lack of necessary support structures. Use companion planting, know when to harvest herbs, and learn the general soil requirements for your plants.