Here are some things I've learned over the years with hard surfaces:
1. What people do to the floor in the time they own/are in charge of the floor before you come into the picture has a great deal to do with how easy or difficult the job will be.
2. Your need to pay attention to detail at every step is astronomically higher on most hard surfaces than all but the most delicate of textile surfaces
3. Mistakes made along the way are much harder to fix than in textiles.
4. Customers expect the job to be easier than it will be, expect better results than usually can be delivered, and are less forgiving of unsatisfactory results.
5. Fixing problems created by prior bad maintenance practices, or your mistakes, are VERY expensive and time consuming.
6. I'm VERY cautious in the use of after market sealers and coatings for all of the above reasons.
6. I've learned more from Bryan Thompson in a few hours than every other trainer in our industry combined over the years. He and Mike put together the best training and reference material I've encountered, and I rely on it (and them) still.