* It's better to over-deliver than over-promise. Yes, your marketing materials were really shiny but the product didn't really live up to expectations
* After-sales support is so bloody important - don't disappear after you've shipped (MiiPC & Cubieboard I'm looking at you)
* Don't lie to me if you say your product is going to be open source or worse, "hacker friendly" (although this was a problem even before Kickstarter and Indiegogo)
* Tailor your communications to your market - the wonderful people over at Ninjablocks/Little Bird Eleectronics had some issues with writing copy that was aimed at general consumers where a lot of their market wanted real technical details
Of course, you'll have different issues to deal with if you're going the VC/startup route rather than the crowdfunding route.
I did a lot of research, talked to some finance guys, and realised I was in well over my head if it was to ever be more than a prototype, so I dropped it. Would've loved to get more info than I could glean from the guys I knew who had supply chain and manufacturing experience: their opinion was "don't do it". Probably a good idea that I listened ;)