This is a hugely debated topic. The minimum amount to put down is 3.5% for an FHA loan (unless you are a veteran or in a rural area, which may allow you $0 down). However, FHA loans can have costly mortgage insurance fees, both upfront and monthly. If you can swing it, the next tier would be 5% down, which would be a conventional loan. The conventional loan doesn't have upfront mortgage insurance and the monthly fees are lower, lowering the overall payment even if the rate is slightly higher. From there, the more you put down, the better your loan terms will be until you get tot eh magic number for down payment - 20%. With 20% down, you can avoid mortgage insurance altogether.
I hope that helps a little. You should really have a more in depth conversation with a mortgage professional in your area.