The best way I've found in the beginning was when I was doing a test run. I wanted to get all 4 aspects of 4 workers to 100% before specializing them. My goal was to have a team of 4 workers who would add specialization to a project but who could also work on other fields as to speed up the game making process and thus reduce downtime from the other workers who finish early.
Found out that they kind of "forget" all what they did when they specialize... So this was really disappointing... However, I was literally swimming in cash by the time I was ready to move to Vancouver. And winning more awards than anybody else too.
So, I'd have to say: at the beginning, forget about specializing your workers until you get about 4 fully educated workers (100%x4 fields). Just keep flooding the market with cheap games. Then specialize the new workers you will eventually hire once you move to another city (or later on, whatever).
The tricky part of this game is the goals. The first game I played, I was already at Montréal when they asked me to move to Vancouver. And the game didn't acknowledged the fact that I wasn't in Vancouver anymore. I was like "WTF"? Had to restart my game.
It is a nice game, but it has its flaws.