This may seem really basic to the advanced users of the game. I was really frustrated and couldn't get cities over around a 20,000 person hump until I figured out these two things. More than anything else in the tutorials these helped: #1 - Hit the fast forward button - your sims won't get educated or healthy until around 2030 despite how much health and education stuff you have. If someone says "I have all health and education and everything but still low class sims" I would say back immediately hit the fast forward button and then make yourself a sandwich. #2 - Cut taxes - 9.0 rate is pretty suffocating for growth. If I have the budget I set my taxes at R$ - 9, R$$ - 7.5, R$$$ - 6. C$$$ - 6, C$$ - 7.5, C$ - 9. Dirty - 10, Ag- 14, Manufacturing - 10, HighTech - 6.5 Between these two i can get wealthy or middle residents and high tech zones fairly quickly as well as a lot of demand for every category besides dirty industry and agriculture.