If you're not in a situation where you feel you're being nurtured to move up within your crew, or if you're looking to transition outside of your classification, like from Camera Assistant to DP or Director, where people outside of your crew would be hiring you, I usually suggest that you stay quiet around your "bread and butter."
There are always exceptions and "the exceptions" tend to know who they are, what they can get away with as far as forging relationships on set with people who can help with their transition. But if you feel you may risk your money job by sharing your goal, don't do it. There are a lot of relationships that have to be made in order to make a move up or out. This can take 2-5 years to gain the trust they will need to hire you. In the mean time, keep working and making money at your current position. That's my opinion.
For more tips and articles by top entertainment industry career coach, The Greenlight Coach, visit www.TheGreenlightCoachBlog.com