Registration Priority for upper-division Electrical Engineering

How hard is it to register for classes for upper-division Electrical Engineering? Will you have to petition? How long are the waitlists/how many petitioners are there? Are you typically able to get all the classes you planned?

What about getting into Phys 9D (Modern Physics) and Engin 6 (Engineering Problem Solving)?

Is there anything I should do to improve my registration priority?

I ask, because I will transfer to Davis from a community college next year.