Didn't find out how much they could afford before looking.
Many home buyers start looking before they know how much they can afford or they jump online and "pre-qualify" with an online service and think they are qualified. You need to know how much can you really afford. If you Bank or Mortgage company hasn't asked for letters of employment, done a credit check or confirmed your down payment you aren't "Pre-Qualified", you might be pre-approved or you might be told you can afford this much but don't believe it. A good Mortgage Broker or Bank will supply you with a written confirmation of your financial ability, maybe with conditions such as the house appraisal and/or CMHC approval. If there are conditions about your financing credit ie; pay off credit card, provide proof of employment, etc. get these things taken care of immediately.
Never thought about their wants, needs, must haves & lifestyle.
What type of house are you looking for? Why that type of house? What are your basic needs and your must haves? What is your lifestyle currently and is there any reasons it could change in the next 2-5 years? These are all questions to ask yourself. Buying a house is nothing like buying a shirt or a car. It's a much longer term investment that has significantly greater impact on your financial well being. Think am i likely to change jobs?, get married?, have to move?, have children? Need additional space in the next number of years. These things can all impact your buying decisions today.
Looking for a Deal instead of a Home.
Unless you are an investor the house you are buying is your home and will be for some time. The best "deal" is rarely the best "home". It's important that when making your buying decisions you think about the future. I've seen people buy homes that have been recently renovated with cheap upgrades that looked good, knowing that in 12-18 months those upgrades are going to need replacing or people buy a cheap house that needs tons of work and they work like crazy in their jobs and or have no skill to do repairs needed. Buy a home that suits your current lifestyle and your best predication of what your future lifestyle will be. Consider your resources & don't fall for the HGTV trap - I can buy a $200,000 home fix it up for $20,000 and sell it for $350,000 - that's nowhere near the real world.
Didn't Consider Resale
In the modern world most home buyers will have to sell their home and usually sooner than they believe when they buy it. Not thinking resale when you buy can have a huge impact down the road. The convenience of being on a bus route (busy street) is great for the commute today but come resale could be a problem. Backing onto a retail space was ok when it was a fabric store but the new fast food joint not so smart. You can see what I mean.
Falling for the Stagers tricks.
First, i believe in staging, it helps homes sell faster and for more money but as a buyer be aware of these things. The windows are freshly painted to hide the wood rot, there's vanilla in the stove to hide the dank smells of mold, the gorgeous furniture, the fresh flowers, the beautifully set dinning room table won't be their when you move in. Location, Price, Size and Condition create value, if a home has those four things then consider it, but don't let a little spit and polish fool you into overpaying or lack of it put you off a great house.
Never got a Comparable Market Evaluation done on the home they bought.
When buying a home make sure that it's priced right. Don't rely on what the neighbour or the seller said it's worth. Ask your Realtor to give you a CMA (Comparable Market Appraisal) of the home. Not working with a Realtor, (another mistake), consider having an appraisal done before offering. Many lenders will take into consideration the Buyer as well as the appraised value of the home when doing financing so if they like your financial position they may over look a purchase price slightly over the appraised value. Don't rely on an online site - house values can vary greatly based on location, size, condition and without seeing a home the online evaluations are at best a guesstimate of value.