There are so many lessons to be learned in a garden that it’s more a matter of where to start, because the lessons never stop.
For instance, rain barrels are highly recommended and very handy. We have two, one by each back corner of the house, and even a half inch of rain can fill a barrel up. We use the water for inside and outside potted plants. However, there are some lessons these barrels have taught us, one being that in warm weather they are dandy breeding places for mosquitoes. So we use mosquito floats, which must be replaced monthly, to prevent mosquitoes from hatching. Plus the barrels inevitably collect plant matter from overhead trees through the downspouts and even though the barrels have screens, the plant matter is so fine that it falls through and ‘marinates’ and the water becomes nasty-smelling. So we empty our barrels to let them dry out and prevent mosquitoes and the waft of the smell of stagnant water. Eventually rain will come and also cooler temperatures, but the barrels require care and attention to prevent problems.
Next, after having used coffee filters for years to cover drain holes in pots to prevent soil washing out when the pots were watered, it finally occurred to me that used coffee filters worked just as well as new ones, with the added bonus that any coffee grounds residue will just act as a bit of fertilizer, since spent coffee grounds are very beneficial to plants in moderation.
Just discovered recently (by desperation, the source of most discoveries), an old toilet bowl brush is really great for cleaning out empty flower pots, because there always seems to be a coating of dirt in the pots, and even if one wants to wash them, it will be easier if they are brushed out first. And that same old bowl brush came in so very handy to brush off my out-door potting bench, because leaves and petals from neighboring crape myrtles and all sorts of debris manage to accumulate on the bench top.
My favorite all-time garden tool is a few old plastic dishpans. I use them all the time to carry plants from place to place when planting or transplanting; to use as a tray when I am potting, so the potting soil which I spill while potting can be retrieved easily; to soak plants or bulbs before planting. I even keep one that is cracked on the bottom because I can leave plants in it temporarily and if it rains, the plants won’t drown.