One of the bests things you can do is experiment and test the waters through observation and trial and error.
Start off humble and get a feel for the environment. Don’t feel afraid to ask questions in whispers.
Try to avoid OOC speak in /s. If you want to ask stuff that isn’t IC, keep it to whispers.
Avoid Goldshire. There is nothing good there. It is not a RP haven, it is a cesspit.
If you want to try out the courier stuff, consider approaching the guild ‘Sunnyvale Ratters’. They might fit you for a human courier.
If you want a gnome, try the Assembly of Uld.
Both these guilds are more than happy to help give you tips and help you ease into role-playing.
But all in all… experiment! Try it and see for yourself.