You can never learn all there is to know about horticulture. Therein lies the joy!
Mother Nature is your ally, not your enemy. Love, know and work with her.
Most plants are stunning 2 weeks per year. Plant with color seasons in mind.
Plants in the Willamette Valley grow larger and faster than garden books say - do not plant too close.
Your soil texture can never be too good. Fix it before you plant.
If "working" in your yard is not therapy and exercise, hire someone.
In gardening, experience is the best teacher. Do it, get it, find it and ask for it.
A back yard must have a private place to enjoy peace. If not, change it or sell it.