Open houses are an exciting adventure, but have their own set of rules. You need to follow them in order to turn open house shopping into a dream house purchase. While they can be fun, but they also require prep work, keen attention to detail, and follow-up. Below I've rounded up the important "must know" items to make the most of any open house experience.Start online. Almost all purchases begin with online research, and home shopping should be no different. Online tools such as Trulia.com allow home hunters to find properties open in the neighborhoods they're interested in. To stay ahead of the game, sites like Trulia have a mobile app with GPS capabilities allowing for new open houses to pop up nearby. This will allow you to quickly swing by and check it out that day!Think of each open house as a "House Buying 101" course. Use every home you walk into as an opportunity to learn more about the home itself, as well as the neighborhood, local amenities and schoolsLook But Don't Touch. Even if you walk into your perfect house, you are not going to buy it that day. You must shop around first. Never make an offer on the spot, especially if you're a novice home buyer.Declare Your Independence. If you love the home and are planning to go after it, tell the listing agent you're already working with a real estate agent. Never hire the seller's agent to represent you in the purchase of that home. You always need an unbiased advocate who is in your best interest to be your right hand in any potential negotiations.Hold Your Cards Close. Don't reveal too much about yourself, your situation or your need to buy. It's especially important to never reveal the top price you are willing to pay. You don't want that information to be used against you later down the line in negotiations.Evaluate the Exterior. As you walk into an open house, pay close attention to the exterior paint and the state of the roof. Does the paint look fresh or is it chipping/dirty? Do the shingles look like they need replacing in the next 2-5 years? Are there large trees nearby or moss growing? What is the condition of gutters or any other key items on the exterior? This is a tell tale sign in what you'll find inside.Walls and Windows. Determine the conditions of the walls. Can you see any significant damage, dents or other red flags to one of the most visible parts of the home? If these visible items are not in the best condition, it may be a red flag and indicate larger issues.Take Pictures and Take Away the Takeaways. Take pictures and notes as you walk around a home. If you see multiple homes in one day, they'll all start to blend together. Gather and keep the brochures or printout information sheets on the houses you see, to keep track. Save them and share with your Realtor.Keep Your Interest Under Wraps. Even if this is is the perfect house for you, it's important to keep your best poker face. Get at least a block away and then call your Realtor. Don't jump up and down with excitement in the driveway or lobby. If the seller's Realtor sees you, you can potentially lose leverage as a buyer.Not the right house for you? "Buy" the agent instead. If you decide to pass on the home, it may not have been a complete waste of time! If you haven't selected a real estate agent, this is a fantastic opportunity to find an agent or broker too. You actually get to see them in action. Is he/she knowledgeable, informative, hard working? Or is he/she sitting in the dining reading Us Weekly while you stroll through the house? And most importantly do you like him or her? Your realtor will eventually become your house hunting team member and you will be spending a lot of time with them. Take their card and jot a quick note on the back to jog your memory later.