Test the hell out of your demo/beta before it goes out the door. You don't need to fix everything before you release it to the public, but you do need to fix all critical and complete blocker issues that you are aware of, and ideally have a list of all other major bugs or missing features lined up (And a road map of how those are getting fixed if possible).

Make your initial backing level super cheap. I'm far more willing to part with $5 on something that might fail than I am with $30 or more.

Have your budget in very good shape, don't forget to account for Kickstarter's take and taxes, and leave some wiggle room in your overall budget when deciding your minimum funding. It doesn't have to cover everything, but you do need to have a plan for what happens when: A) Kick starter isn't going to cover all your costs, and B) Costs become higher than you expect.

Also, get your core fanbase lined up and ready to go on day one of your campaign. Do NOT expect to start your campaign the day your kickstarter goes live. Your kickstarter is part of the "Last 10%" of your startup campaign, not the beginning. If you don't have data suggesting that you have enough customers to met the bulk of your goal 'tomorrow' if you were to launch your campaign today, then you have more work to do.

Put lots of effort into the video production. If the audio hisses or sounds like you're underwater, then you are clearly some fly by night group doing this on the cheap, and aren't remotely serious about it. if the lighting is bad, or it is all one single long take with lots of ummmm, and uhhhhhs, and, ands, then you're probably some kid with no clue what you're doing.

Find someone who can help you edit your promotion video and update videos, or learn to do it all yourself. (Consider Adobe Creative Cloud if you need software tools. Bit of a bite out of a monthly budget, but I've found the on going cost easy enough to find ways to manage.)