1. Design with your factory. Finding a good supplier is important but the real work starts once you've shaken hands. Your factory is your greatest resource as a presumably inexperienced hardware designer. It's like having an expert-level consultant work on your project for free, so take advantage of it.
2. Keep it extremely simple. MVP applies here. Your project will probably fail if it does not have the absolute minimum viable number of hardware features. The majority of your effort should be spent thinking about how to simplify your designs. Avoid moving parts if possible, and design parts that can be produced with simple tooling.
3. Your margins should be higher than you think. Think long and hard about your pricing before you launch your Kickstarter. Chances are, your MSRP is optimistically low. Bringing a hardware product to market involves lots of expensive rabbit holes. High margins will save you from death.
[1] https://www.kickstarter.com/projects/rideye/rideye-the-black...
[2] https://www.kickstarter.com/projects/voltus/voltus-mobile-po...