If the concept of crowdfunding sounds too good to be true, that’s because it kind of is. The market is oversaturated, and unless you already have a recognisable name you will find it difficult to stand out.
Set the rewards tiers to appropriate prices that will cover the reward item AND the shipping. Don’t forget how expensive it can be to ship a small package across the world. The last thing you want is to raise a few thousand bucks and blow it all on reward fulfilment … again, I speak from experience.