Generally cash game players have an easier time transitioning to tournaments than the other way around.
In a tournament, remember that you can't re-load, so chips are worth more. You can't afford to play speculative
hands like small pp's or SC's unless the blinds are tiny. Otherwise you're going to bleed your stack off.
You can also generally make smaller bets, since as previously stated, the chips are more valuable to the individual, they are (should be) less likely to call.
Lastly, maximizing expectation isn't as crucial as picking up chips. In cash, you determine the best bet size by multiplying the likelyhood of a call by the size of the bet. However in a tournament, choosing a smaller bet size with a greater probability of being called is often the best play, since adding chips to your stack is so important.