"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.
He must be dedicated to reading before applying them here and most time what he may want to asked has already been asked, so what he needs is to go through those posts, study them before coming up with questions. It to my knowledge that most start up individuals are not eager to study what they does is just come up with they want to ask and post straight without knowing that similar questions has been asked already.
And less moment to post.
If they understand that very correctly then they wouldn't ask much question than reading things across the forum to know what they want/ not want.