An artist needs to keep sketching. For many, this is a habit that comes naturally. It’s spontaneous and rewarding. If it’s not a habit, don’t worry. Keep doing it, and it will become one.
However, as rewarding as sketching is, keep a camera nearby. Take snapshots of everything that inspires you. With digital cameras today where you can pop the card into the computer, there is very little expense.
There has been a lot of arguments as to whether one should or should not use photography as a resource in painting. There are some artist that totally oppose it, and others that use it almost exclusively. I personally believe whatever it takes for an artist to achieve their goal on canvas, paper, or board, then so be it.
I find the photograph is a great guide for factual information. I seldom use it for color composition since it tends to be monochrome or tonal. Remember, the digital colors are in mixtures of cyan and magenta and a paint pigment can’t pick this up accurately. In other words, when mixing pigments, do your work with nature to get the proper colors.