If you are a first time buyer, the first step to purchasing a home is to figure out how much home you can afford and getting pre-approved for the loan. When determining your budget for buying a home, you should first sit down with a loan representative to find out how much of a loan you can qualify for and what the monthly payment will be. Once you have an idea of your price range, the loan officer can provide you with pre-approval letter stating the amount of the loan you are approved for and the interest rate that your loan will have. Your Realtor will need a copy of this letter so they can submit it with any offers that you make.
When the listing agent(representing the seller) receives offers on their clients property, the ones that do not have pre-approval letters attached to them are not taken as seriously because there is no verification as to whether or not the buyer can actually get financing. Submitting a pre-approval letter with your offer makes your offer more "real" to the other side. The only instance where a pre-approval letter isn't necessary is when the buyer is paying in cash, which is not common. In this scenario, they buyer would need to submit a verification of funds with the offer.