I found a pattern I really wanted to make -- a Pat Sloan applique pattern but I do it with Needleturn rather than fusible. I went to buy the fabric at a nice LQS and asked them to help me with the different colors. It helped me to see what I DIDN'T like that they picked and I switched it for something else. By the time I was working on a block, I switched out two of the fabric for stuff in my stash.
I have made mistakes before but you will find as you go thru this that when it isn't right, you will see it.
One person suggested using cross stitch floss to help you and that is a terrific idea!! I have a ton of floss and will use that in the future for sure.
Remember -- you are not marrying your choices -- it is like a college mixer -- if you don't like something, find something better. I used to let it drive me nuts but I don't any more and I am usually happier with the result.
Good luck and don't be too frustrated. What is interesting to me is how my taste has changed to more contemporary fabrics and patterns -- I was all about repos before!!
Pat