There are no rules that say you have to use all the colors in the quilt block pattern. I often will make a pattern that calls for several fabrics with only 2 or maybe 3. Sure you change the look of it, but that is half the fun. Just try some single blocks and see what you think. Remember, the only rule is that there are no rules. Just have fun and don't be afraid to try new things.
Just jump in with both feet. The worst that will happen is that you won't like the block and you will try another one. In the end, you may have one pretty sampler quilt!