I also usually sit the new player next to someone they know who can also help explain rules when I’m busy doing other things. Especially as a DM or GM, it gets harder to split my attention between answering questions and running the rest of the game smoothly, and most of the questions are ones that anyone who’s played the game for a while can answer.

Also, definitely get the other PCs on board. I find that I need to remind my players that you can justify your character doing almost anything if you want to, even if you’re committed to roleplaying in-character almost all the time, so you might as well justify them doing something cool that moves the game forward, rather than sandbagging because “its what my character would do”. This is especially true of new players, who will interpret in-character rejection as out-of-character rejection.