Hate to say it, but the more you try to prove those intentions are sincere, the more people are going to be skeptical of your claims--especially here, where it seems like every other ICO is a scam with fake profiles and nonpayment of bounty hunters.

More important IMO would be showing why your project is worth investing in in the first place, i.e., that it's useful and worth investing in.  I've no doubt you'll get a lot of speculators interested in it, but they'll flee and sell everything off as soon as whatever you're selling goes to market.

Whatever you do, marketing is something you'll have to spend money on.  There's no way you'll get interest unless you advertise, and that means paying people to do it.  I don't know of any project thus far that hasn't had some sort of campaign involved.