If you are intending to produce a new RPG I see just a couple basic reasons to do so:
1. Mechanics. You have ALREADY come up with new mechanics and want to make an RPG based on them. Or perhaps you have found that NO OTHER RPG has mechanics that you like, or that will work for the RPG you have in mind - nothing you can pattern your game after, altering someone else's mechanics to stand adequately as your own, or no open source system of mechanics that you can put to use. That means that if you can't then come up with entirely new mechanics yourself you'll have to PAY someone to do that for you, and they will then (possibly) want rights and payments should THEIR work prove popular and profitable in the long-term beyond a one-time payment for a basic mechanical system. After all, if your RPG needs new mechanics to make it interesting (or to work at all) but yet all the stuff that is NOT mechanics is too valuable to just let it be seen by the public you can dispense with everything else about your RPG until you've studied enough RPG design (for which I don't think there are any community college or online university courses) to do that part of it yourself, or you are able to start paying someone to do it for you, or you ALREADY have a legal arrangement cooked up that will enable hiring the game designer you need to handle the mechanics end of your RPG.
2. Setting. Whether it's generic fantasy, scifi, modern-day, supers, or magical girl anime, or whatever, you have a vision for a SETTING or a genre that either hasn't been done before or that you hope/believe will prove enticing despite what HAS been done before. Sometimes a good RPG setting can be badly undermined by a poor set of mechanics, so that puts you back to square one needing a set of mechanics to fit your setting. But just having great mechanics doesn't guarantee RPG success. If nobody is interested in the setting you build around those mechanics they'll just be forgotten. Does your setting NEED all new mechanics in order to accomplish something?
Frankly, I think your biggest thing is going to be #2. Until you really have that in a fairly advanced state - what the world looks like, what the PC's should be able to do (even if you don't know HOW they will do it yet), what kind of gameplay experience you are after, and the fact that you are asking for random ideas for mechanics tells me that your RPG isn't ABOUT the mechanics. But then what is it? Is it a storytelling game? Dungeon crawling? Highly detailed and crunchy, or very loose and freeform? Answers to those kind of questions will inform all your choices about mechanics - what degree of granularity you need for determining PC success/failure, how deeply PC's/players will be able to influence results etc. Will it be skill based or level based? A d6 dice pool type of system will play far differently than a d20/D&D system and which does your SETTING really need to make it do what you want it to?
And it strikes me as quite disingenuous to ask on a public forum for free help in designing your RPG by providing you with the mechanics for it, but you consider your core "idea" SO valuable that it would risk being STOLEN and having someone either beat you to the punch in producing an RPG of their own based on it, or let you do the heavy lifting in getting it completed and then just sue you to seize the whirlwind of profits you expect to reap - despite the fact that you are, at this point, seemingly asking for free public assistance in designing your mechanics. The latter, of course, means that ANY public suggestions of mechanics for your game that you then actually USE for profit are going to be risking lawsuits anyway, saying, "I came up with that idea for mechanics and now you owe me because you're using them and not giving me my rightful share, so not only do I get payments in perpetuity for every copy of the game sold but you pay me X in damages for trying to cheat me out of my idea." Or maybe you WOULD be safe if you take a PUBLIC idea for mechanics because it was offered freely and openly. Not being a LAWYER I wouldn't be the one to ask.
I'm being a real wet blanket here, but seriously - if you're going to publish an RPG for profit you either form a friggin' company and pay your employees and have A LAWYER work up employment contracts laying out what rights and payments anyone will get, or you do it all YOURSELF, mechanics and all, and then STILL pay a lawyer to properly advise you on how to protect your intellectual property and yourself from predatory legal actions, including another game company suing saying, "Those are OUR mechanics you're using..." whether they have a leg to stand on or not.