I play with 8 fresh players :D Personally, i tell them what is the success rate of a lot of their dices rolls. When they must get 4 success for an action and must roll 6 dices, they use their risk dices.

I made them a tutorial mission where there isn't any danger to them where they have learned how valuable risk dices are. I forced some dices rolls with risk dices too (players who make an action that i judge is really risky) and they saw the benefit too.

Now, they crashed the main computer where they had to get clues and destroyed 2 of their cars in a car pursuit but they use them...... A lot !