Clone Requests are a bittersweet thing in the DIY world. On one hand, they are extremely popular, and people love finding out the recipes to their favorite e-liquids. On the other hand, many DIYer's don't try many different juices. This will help you get the most out of your requests.
1. Popular Recipes
Requests for popular, well known, best selling e-liquids, will much more likely have a recipe, than your local juicemakers e-liquid. No one has heard of "JimboJohns Backyard Burner" before, so don't expect anyone to have a recipe for it. But "Naked 100's P.O.G." is an extremely popular mix that has multiple recipes associated with it. I'm not saying only post popular e-liquid requests, just understand that you may be shooting in the dark with some e-juices.
2. Help me, Help You
If you're working on a clone, make sure to post all the information you have on it, and all the recipe iterations you've made, to help others understand how close (or how far) you are from nailing that recipe. Collaboration is the best resource for mixers.
Cloning and remixing is one of THE most difficult things you can do in mixing. We know you want that recipe to Unicorn Milk. But they take time. Look at #2, and understand these things take time. It might take 3 - 6 months to get even remotely close to a recipe, where some might take a couple days. Be patient.
These three guidelines will help you get your recipes much quicker and also maintain a strong relationship with the mixers involved. Hard work and patience goes a long way!