Hi!
Sounds like you have received good advice regarding "protecting" your game idea. So, instead, I'll give you some good advice on the practical matter of collaboration:
- Know hat you want your game to be like and how it will be played before you ask for feedback. As Pundit mentioned, don't compromise this vision, unless it appeals to you personally. You want to design the game that you would want to play, not the game that you think some faceless demographic would want to play.
- No matter who it is (Even if through some fluke you get Gary Gygax to check out your game), filter their advice through the lense of how you want your game to be played. for instance, someone may say adding Buffy/Angel style Drama points will make story telling easier for players. But if your game is not about story telling, then this is not good advice, see?
- Listen to what they have to say, and ask questions if you are not clear what someone's feedback means. You will find that very few people are willing and are able to spend the time to read/play your game, so when someone does take that time, make sure you understand exactly what they are saying.
- Tell anyone who is helping you with your design exactly what kind of feedback you want. If you want a proofread, be sure to say so, if you need someone to actually play this game with their group, again say so, etc.
- Set collaborators up to succeed. By this I mean, communicate your vision and goal of the game design. Explain the genre, play format and feel you are going for. Then you are more likely to get feedback that will help you reinforce that vision.
- Don't criticize the merit of feedback you receive. Obviously, feel free to criticize someone's ability to follow instructions or spelling/grammar/communication errors. But don't give criticism like that is a bad idea or your statement is pointless. People who have been disrespected after giving you assistance are sure to tell their friends, thus reducing the potential pool of playtesters/collaborators. If feedback you are given seems wrong-haded to you, ask what they mean or why they made that advice, try and turn it around if you can.
- Don't get your hopes up, sometimes it is hard to get feedback. Many people will offer to help, but then not follow up on that offer, many people will ignore your plea for help. Its not personal, its just that many people are working on their own designs or are full up in gaming groups already. don't get discouraged if it takes time to find a good reliable playtest group or two.
Finally, pod publishing, like with lulu.com, is very inexpensive (free for most services) and the quality is good and the overhead on your part will be minimal.
Good luck man!