"What are the biggest mistakes I should avoid as a newbie"?
You don't need to shy away from mistakes, if you don't make mistakes, if you are really a beginner, see them/other beginners how they navigate this forum, Under your topic post they have shown the rules that must be understood and studied as in general.
For this reason, if you carry out your activities as usual without making mistakes, you will appear calm here, the members here will guide you well, As long as you have the will to ask questions and want to learn, especially about Bitcoin and so on, keep doing positive things and the results you will automatically get will be positive.