From my experience, I have seen that one of the most common mistakes people make when applying for a mortgage is not having a clear understanding of their finances. Many individuals fail to calculate and budget their expenses accurately, leading to overestimating or underestimating their mortgage affordability. Another critical mistake is not shopping around for the best mortgage rates. Many people stick to their current bank or lender without exploring other options that could potentially offer better rates and terms. Lastly, not having all the necessary documents prepared and organized can delay and complicate the mortgage application process, causing unnecessary stress and frustration.