As I have taught over the years I have come to realize that not everyone can visualize what something will look like...later...after it's been woven.
If this is the case, then I strongly recommend people weave samples. Sampling is the only way to know for sure how something will turn out, especially how colours will look after being woven together.
I've been learning about colour in weaving for a long time because I wasn't very good at choosing colours to put together to make a pleasing cloth. I studied colour theory. I wound little practice warp wrappings. I dyed yarn. But none of those things reflected - precisely - what happens when you take one colour and cross it with another.
Gamps of various colours then became my most effective way to learn how to visualize.
gamp of tertiary colours
gamp of 'neutral' colours
gamp of pastel colours
One of the big complaints about weaving a colour gamp is the expense. You need to buy a whole cone of yarn for just a little bit of each colour. So for several years I sold colour gamp kits. In addition to the more usual primary/rainbow gamp, I offered tertiary, neutral and pastel kits.
This allowed people to explore a greater range than they might have been able to do otherwise.
For some people they just don't know what is going to happen when they cross purple with, say, a red/brown. Orange with green. Black with yellow.
If you've never done it, how would you know?
However, if you can't afford to buy all the yarn, you can study what other people have done.
For example, you can look at something you really, really like (or dislike - both have lessons) and examine it for what the weaver/designer has done. What colours did they use? In what proportion? In which weave structure?
The picture at the top is the next painted warp for Tien's class. I don't know how much she will be able to cram into her suitcase when she comes in June to teach her workshop and seminars on colour at the conference but I'm sure she will bring some. What better way to learn about colour than to actually see - and handle - woven examples that show precisely what happens when weft crosses warp?