What are some decisions you regret taking when first starting to invest? Help!!

[Sigyfredo Iniguez]

Hello everyone my name is sigyfredo and I'm 21 years old , so I want to start investing into rental properties and start flipping houses, I do understand that reading books will help me increase my knowledge, but wanted to ask the bigger pockets community what are some other ways y'all did to increase your knowledge?

Also I wanted to ask, when y'all first started investing what are some mistakes y'all did that affected you long term or even short term.

Thank you all.