Even as the majority of home buyers will make emotionally driven decisions within the first 5 minutes of seeing a house, you should still try to be rational and think about the entire decision at hand.
When you are viewing a home, make sure you study the layout. Is the floor plan suitable for your situation? If you have children, is there adequate room for them to play in? If there are stairs, will they become an inconvenience? Are the bedrooms too close to the living room? Are you thinking of having children? Will this house be big enough for your future family? Is there enough storage room/closets to store all of your belongings?