Getting ready to dye naturally

Might as well get the basics down for those of you who are new or relatively new to natural dyeing.  There is not a lot you need to begin, and experimenting on your own is as lot of fun; but if you are wanting results that you can begin to predict a little and possibly see again and again, there are some things to know up front.
I has been raining heavily over the last week.  If you are an outdoor person, this would sound horrible.  If you are a dye person however, this is a great thing!  Rainwater and more rainwater.  This is truly a Godsend for the natural dyer.  Water plays a very important role in the dye process.  The ph (acidity or alkalinity) of your water can change your dye colors drastically.  Many flower dyebaths are acid.  If you dye a fabric in the acid dyebath, you may change that color by dipping the fabric in an alkaline solution after dyeing (i. e.: baking soda solution, or an alkaline soap).  Most rain waters are in the neutral zone on the ph scale, depending on where you live and what the rainwater passes through on it's way from the sky.  If you live in an area like Los Angeles, your rainwater will pick up all kinds of particles from automobile exhaust fumes that change the acidity of the rainwater.  If you live in the Serengeti (and are lucky enough to get rain), it would be less acid.  So water is your first need in natural dyeing.