Never invest more than you can afford to lose which is the most important lesson. Also need to learn charts, TA etc. and watch for whale movements which is very important these days to avoid being a victim of market manipulations.
For me I learn to avoid being greedy in attitude, and to have satisfaction in every transaction being made and decided to go through. Because crypto market is unpredictable so it is really need to have strong determination in every investment made and strongly work with it. Be aware and anticipate the possible looses and move ahead always.