Dreamcatchers are best made for or by the person. Dreamcatchers made by Native American tribes for money are not medicine, they're novelties. I'm sure you could charge it and focus on the intent of it catching nightmares and allowing only good dreams to pass through the opening. I would suggest adding a symbol of your spirit animal sitting over the opening or to the side of it. They serve as a sort of gatekeeper, additionally keeping watch that only the good dreams make it through. Colors of the beads matter, but you would need to know what tribe made the dreamcatcher and look up what colors correspond to what meanings to that tribe. For instance, robins egg blue is considered a protective color for the cherokee and they would paint there houses this in order to keep bad spirits out. So the light blue color would prevent malicious spiritual influence out of your dreams if it were incorporated into the dreamcatcher. I've heard of people adding charms to their dreamcatchers as they make them, ones that represent the person they are guarding over. I personally never heard of this until recently and it seems a little more modern. Original dreamcatchers were made of bent green wood and natural beads, while novelty ones usually have a metal hoop with plastic or glass beads.
They are nice to make. I've made quite a few. Very easy when you get the hang of it. There are instructions for them all over the web, although I learned from my mother way before I even knew what the internet was or had any access to it.
I love the look of the spiral ones, although those just seem artistic and they gather dust very badly! I would like to make one out of silver and copper. I think it would make a terrific light catcher if I use lead crystal beads strung throughout the web. Hmmm, now I think I know my next project! =D