There are many things to consider when touring a home when you first arrive at an Open House. Some things you can tell even before you enter the home. I guess it depends on how you came across this Open House to begin with.
If you found the property on the Internet like Trulia or Realtor.com then you may be unfamiliar with the location. The most important thing to remember is location, location, location. While driving to the Open House make sure you are observing the neighborhood. You can always make cosmetic changes to home but you can't pick it up and move it. (or at least why would you want to). If you are following signs you probably are familiar with the area and the neighborhood. I would always take though of the neighbors on either side.
So with keeping that in mind you should always have a list of "must haves" when searching for property. What is it that you can not live without when buying a house? Do you absolutely have to have a pool or a huge family room? Are you willing to paint even though you prefer "move in ready"? Having a list with you will help you go through the home being able to check off items that are simply a must in your new home.
A lot of times buyers see a home at first and emotionally fall in love with it and forget to look for things that are a necessary must to them. Such as walk in closets or extra storage, multiple outlets in the kitchen, a large backyard, etc. Seeing a pretty home sometimes makes buyers forget about what's really important to them. That's why a "must list" is good to have.
When you are looking at the home to be afraid to open kitchen cabinets or closet doors. Home owners know this will happen and you shouldn't be shy about it. Look under the kitchen sink, see if you see anything dripping or better yet how clean does it look? Looking at these areas is not unethical when buying a home. Ofcourse you don't want to open any furniture drawers or T.V. cabinets because that has nothing to do with the home. But checking whether or not the closet is a walk in is expected, don't be shy.
When walking around the home is best to determine if the "bones" of the house work for you. Does it have enough bedrooms? Does it have that large family room you are looking for? Replacing carpet, paint, or putting granite in can all be considered into the price you want to offer and done after close. Having to remove a wall or add a pool are all really expensive if you are thinking of having to do those things once you move in.
Don't be afraid to ask a Realtor lots of questions about the property that's what they are there for. You won't be wasting our time, it's what