I learnt that - 1. brandable reseller value has gone down 2. Even liquid domains can fail you. if 4Ls don't surge in 2020 i will have loss. 3. Bin works best for my portfolio instead of make offer. 4. Outbound can be managed well only with team 5. If you see any huge sale and find similar domain expecting same range price. Bad idea. 6. Crypto domains. I got into crypto domains only in 2019 and it failed me. Trend change faster than you imagine. 7. Learn to use different tools. I learnt few more things which i may mention in comments. what are your lessons in 2019?