Go to websites, magazines and catalogs. See quilts YOU like. What do they have in common?
I don't use kits at all, but many people use them to get things they like without having to figure out what that would be. You can get very attractive quilts this way.
In general, a locally owned LQS will have staff who will be delighted to help you with this sort of decision. They will generally set up a "kit" for you, if you want.
What I actually do, however, is buy fabrics that I like. Often they are in the cool range of colors, although I will almost always buy a really good deep red, purple or a strong blue, as they are not that easy to find. When I pick up a theme fabric, I go to my stash to see what I like that goes with it.
There have only been 3 or 4 of my 430 finished quilts for which I bought all the fabric at one time. I don't mind having fabrics sit a while in my stash until I find the right place for them. For my garden maze quilt, I was given a yard of really great floral fairy fabric. The green I used was left over from a quilt several years ago. The magenta, I bought last summer, just because. I have no idea how long the off-white sat in my stash. Any good tone on tonemay have a host of good uses.
Until you are sure of your own taste, pick all the fabrics for a quilt at once. You do have taste, or you would not be able to select your own wardrobe. Quilting is much more forgiving than clothing. Do, however, start with relatively simple designs, so that you are not overwhelmed.