Here is a summary of some of the things I've learned in a short time on this site:
1 - Algae got a foothold and multiplied quickly because I did not check and maintain the recommended FC level often enough (in relation to the CYA level), allowing it to drop too low before boosting it back up. I actually boosted it back up to the low end of the range (being too conservative in chlorine application) rather than the high end, therefore allowing it to drop too low during the day.
2 - I can conserve the powder in my K-2006 test kit because the 2nd dip of powder isn't needed if the sample turns red with the first dipper.
3 - I can conserve even more powder in my test kit via using the 10 ml (0.5 multiplier) level during most of the slam process.
4 - I don't need to purchase "yellow out" from the pool store. I can get rid of algae by slamming.
5 - From direct observation and experience, I've learned that there is something wrong if the water is not crystal clear. It's cheaper/easier to deal with if dealt with sooner, rather than later.
6 - Sunlight eats chlorine (knew that already). Algae eats chlorine also, very quickly if problem is not dealt with quickly.
7 - CYA level determines how much chlorine is needed. Too high a level requires a lot of chlorine...
8 - Most of the powdered sanitizers add stuff to the water, stuff that can build up too much over time. Liquid bleach, although bulky, is simpler and does not add anything significant to water except a small build up of salt level.
9 - Most chemicals that you would purchase in a pool store can be obtained otherwise more economically elsewhere under their chemical name and will do the same job.
10 - A recommended test kit is mandatory to knowing what is going on and developing a successful plan to solve any problems that may arise.
I've learned much more than this but these things are a good start at compiling a list.