I'm doing mine by weight, too. I got so confused trying to work out rates for all the countries that for now I'm only shipping to NZ, Australia, USA, Canada, UK and Ireland.
I'm hoping to open my shop next week (I've been working on it for hours a day this past week) but I knew I'd never get it open if I kept worrying about working out shipping to everywhere.
I'll slowly add other places to ship to once I've opened, but the above countries are where my Etsy and other online sales have all come from, so made sense to start with them first on SupaDupa.