Have fun and experiment. There is no cookie cutter set up.
Remember that you can always get rid of a particular boff skill and replace it with a different want and train that up, so your never stuck with what you go for at first. And it doies not cost CP, or dilithium. You just spend the officer points you get with your experience points. Noone will ever be able to use all the points you will eventually gain anyway, so don't ever feel like your just wasting them when you change your mind about some Bridge Officer skill you trained up to level 9 because your going to wipe it and retrain a different skill to level 9.
I personally go for two TAC's, One Science, and One Engineer. (Plus Myself)