But I think that you are allowed to add a trait if you have University Life. The quick way to curry favor with a social group is to buy 4 or 5 of the gain influence rewards at 2,000 LTHP each, total cost 10,000 LTHP. Buy them all at once, as you have to be at level 10 and influence deteriorates over time. (Actually, I looked at the rules, and nothing is said one way or the other.)
The various celebrity opportunities will help you, and if your sim can get the Opportunistic LTR, that doubles the amount of celebrity points you get each time. Also, if those 1-star celebrities interact with each other, they'll gain celebrity points. Finally, I'm not sure how much of a celebrity your sim has to be to max the career. I know my decadynasty heir got to the top of the director career without being a 5-star celeb. Hope this helps!