Upgrade your graphics so they look more professional
Get your writing proofread (many people associate grammatical errors with scams)
Release a detailed post about the inactive accounts, how your project can help and why people should get involved
Try using the #minnowsunite tag (or another tag that might directly reach newcomers)
Tell people who’s behind the project so they can trust you more
Have a contest to find a list of fun and interactive questions people could answer daily and make resteeming a requirement for entry

If you’re not sure where to get the proofreading and graphics done, you could make a steemgig and hire a steemian to do it. If you need it done more cheaply, try simbi.com. You can barter for the services there. Hope this helps :)