#1. NOT HAVING AN UPSELL
I launched a product in 2006 and made $250,000 in a week (great) but DIDN'T "have time" to create an upsell or downsell for it (ouch!). BIG mistake, I had plenty of valuable things I could have offered and generated maybe $100k+ more sales from this but didn't realize importance of upsells and downsells back then
So - what's been YOUR biggest marketing mistake?