Here is a quick tip you can use to help you weed out a lot of proposals.
A lot of outsourcing companies bid on a lot of projects at once. In order for them to do so, they frequently bid without reading the details of the project description. You can tell who these companies are by the generic copy in their proposals.
To weed out these companies, ask a very specific question in your project description that they would need to answer in their proposal. The question could be related to your project like:
Please let me know in your proposal, what platform you would recommend for this project?
Please let me know if your proposal, what design choice you would recommend and why.
Or if the project is fairly straight forward, you can ask an unrelated question like:
What is your favorite fruit, and why?
What kind of music do you like to listen to?
The answer is not important (although it can help you gauge their personality). You are more interested in seeing if they actually answered your question or not.
You may be surprised to find how many proposals do not answer these questions. If they can’t follow your instructions in their initial proposal, what kind of quality can you expect from them in your actual project?
So now, instead of having to choose from 20 different companies, you may only have to choose between 5 or 6.
Good luck with your project, and let me know if there are any questions on outsourcing that I can answer for you.