There are many reasons that your transaction may fail, despite having a willing seller and an able buyer. You, the buyer, will have very little control over many of these components, but there are some circumstances for which to prepare. You can definitely expect to navigate through an inspection, appraisal, and title process.  

Inspection

It is in your best interest to have an inspection completed. Again, it's good to get a referral for the home inspection. You can have two different inspection companies deliver two totally different reports, so it's a good idea to use a company that you trust to be both thorough and also fair in their depiction of potential issues with the home. When purchasing a used home, it is typical to expect reasonable wear and tear. You, the buyer, should not expect a perfect inspection report, and it is unreasonable to expect that the seller correct every detail or to drop the sale price to accommodate those fine tuning details to your satisfaction. The inspection is to get a realistic snapshot of what you are buying, and to uncover major deal breaker issues. 

To some extent, further post-inspection negotiation can overcome some of the inspection findings. Many sellers are willing to correct those issues prior to close. Even big issues can be professionally corrected, so don't freak out if you discover something in your inspection report that causes you uneasy feelings...like mold. Over the years, mold has become a fear invoking word that sends buyers running away screaming for their lives. The truth is, a lot of typical household mold just needs to be cleaned up without harm to any of the occupants. It's totally reasonable for a mold remediation company to come out and assess the damage/danger of the offending mold, and then to recommend a course of action to clear it up. Based on the findings, you will have the opportunity continue with the sale or not. You can have the seller get it handled, or adjust the sale price to accommodate for you to have it handled, or you can back out of the deal. Other possible big issues can be handled the same way. Your inspection is helpful for both parties to achieve a fair sale.  

Appraisal

The value of any item is usually determined by how much a buyer is willing to pay for it. When people hear the word "appraisal" they assume that it means the estimated value of any particular item. In real estate, the appraisal isn't actually the value of the property. It is essentially the maximum amount that a financial institution will lend a buyer to pay for the property. You, the buyer, may love the house and you may be willing and able to pay for it. Unfortunately, your opportunity to get a mortgage for the agreed sale price can be destroyed by a low appraisal. In those cases, the seller will either have to drop the price, or the buyer will have to come up with the cash to bridge the difference of their mortgage amount and the sale price. Sometimes the buyer and seller will meet in the middle, and sometimes the deal falls through. The prospective appraisal should be taken into consideration when writing the offer and can even work into your strategy. Your agent should be able to coach you on what to do . 

The successful sale of a property is contingent upon many factors. Some others are clearly explained in Contingencies Part 2 of the buyer series.