This again depends on the type of loan you get. For an FHA loan, you will need a minimum down payment of 3.5% of the purchase price, plus you should plan on another 2%-2.5% of the purchase price for closing costs. The more more money you can put down, the better options you will have, including not having to pay mortgage insurance premiums. You should also account for after closing costs, including any moving or repair costs, and having the first couple of months' payments on hand. Here's a calculator
that can help you determine how much you should put down for a new home, and another one
to help you determine what your closing costs might be.