You don't have to start with a loan officer, but it would help.
First, figure out your budget. How much do you spend repaying credit card debt, other loans, and so on. How much you spend on everything else. How much you save each month. How much on housing right now for rent, utilities and the like. Do you have any room? If you're spending all of your paycheck (which is hard to do if you've saved up a down payment), then you'll have to stay under your current rent.
There are also a couple of guidelines to consider. Banks don't want you spending more than about 40% roughly of your gross monthly income on all your debts, which would include your new home. Generally they also limit the property loan payment (with taxes and insurance) to about 33%.
Second, look around at where you want to live, and how much the type of house you want is priced at. If your type of house runs $100k, then you can figure you'll need about $900 a month to pay off a 30 year mortgage for a house like that. If you can't fit the $900 into your budget you figure in step 1, time to recalibrate. Either you need more monthly income or a less costly house.
Third, now you need to see where you stand on your credit. Getting the answer doesn't mean you're stuck with proceeding to borrow the money and buy a house. Loan officers don't charge you to see where your credit is and get a quote for a particular loan amount. You will be committing yourself when you start signing papers. Before that, you can check out the deals from a couple of different sources. Rates are at historic lows right now, but qualifying is more difficult than it has been in a decade.
Credit scores are important and they continue to climb upward out of reach of many people. When sub-prime loans died, reasonable alternatives to no loan at all died with them. So, you'll need to contact some loan officer somewhere to get past this step. You'll also get to learn about types of financing, like VA, FHA and conventional from your loan officer. Most of us loan officers went through what you're going through and don't charge anything until you're ready to sign a contract, and then that money applies to getting the loan for that property.
Fourth, now start the actually looking. You will know your budget and have gotten an independent opinion of what you can afford. Your looking should first focus on where and what type, and then narrow down the list by what amenities or other criteria you would like. Some people start the 'where' with which schools they want. Others start with the type and rule out condos (because they don't want neighbors) or rule out single-family (because they don't want to mow - but they could pay someone else), but how you prioritize your list of needs is your business. A Realtor can help you think this through.
Maybe 2 bedrooms is okay, but you can actually afford 3 and 2 would be harder to sell later, or maybe you just can't afford 3 because of your budget. Talk to your Realtor and get some sage advice. Many of us Realtors were once in your shoes and we want to help.
Typical buyers look around on the Internet or have Realtors send them listings that meet the buyer's criteria. Then, when something good pops up, their Realtors takes them out to see the property. Many buyers will look at a 8-10 properties before choosing. Some will look at dozens. The better you communicate with your Realtor, the less time you can waste seeing inside houses.
Just one word about credit. You might find out that your credit scores aren't that great and you need a little time to get your credit squared away. The time it will take is worth it. The rates do penalize people who have less than good credit. Last year it didn't matter if you had a 580. Now it does. Less than 620 pays a slight premium to those with 680 or better. The good news is that it can be fixed.