Before we purchase new plants for our gardens, we should always read the plant tags carefully.
I confess I haven't always practiced what I am now preaching. But tags tell us the site the particular plant requires. For example, if it says a plant needs good drainage, we know to plant it on a slope or in a raised bed where there is no chance water will sit.
The tag also tells us if a plant needs sun or shade. I have killed many plants by ignoring their light requirements so now I am very careful to follow what the tag says.
Also when combining annuals in a pot, it is essential that we choose plants with the same needs. It's not a good idea to put plants that like a lot of moisture with those that don't or plants that like full sun with those that flourish in shade.
And beware of the differing requirements for fertilizer.
Remember not to combine in the same pot plants that deer avoid with those that they love. Deer usually avoid plants with a strong smell, a bitter taste, or an irritating (to them) texture. That's why they avoid fragrant peonies, Oriental poppies that contain bitter alkaloids, and fuzzy textured lamb's ears.