...come up with a concept, and shoot it to Olan via PM, Loki.
Once he approves your concept and you get to the point where you wanna put more "meat on the bones" of your concept character, he (or one of us other Trek-geeks) can help in fleshing out the details.
There's room for characters in all departments, by the way... By way of giving your concept a starting push, the departments are:
Command/Conn - Command includes the commanding officer, XO, and their administrative-assistant types (Captain's Yeoman, for example)... CONN is the pilot's contingent, including Helmsmen, Flight Control Officers, Shuttle Pilots, etc. Command and Conn personnel wear the Red uniforms.
Sciences and Medical - pretty much self explanatory. You're a scientist, medic, lab tech, ships councellor, etc. Science is a fairly large dept aboard the Discovery, of course. All kinds of "sub-fields" you can explore with characters here... xeno-botanist, biologist, etc... Science personnel (including medical and councellors) get the groovy blue uniforms (and are often referred to as "egg-haids" by Mac... even though he married one)
Operations - these gold-suiters are the folks what handle day to day operations on board the ship. If it needs to be planned, made room for, coordinated, issued, etc, Ops are the folks to see.
Tactical/Security - May favorite departments (an' don' ye be bandyin' aboot doon here tryin' ta blow smoke up me kilt, either, haggis... if ye wairk fer me, ye bloody well wairk, aye?!). Again, self explanatory... Security officers, tactical personnel (the folks that fire the phasers), etc... Also wear the golds.
Engineering - To be super blunt: you fix stuff and make sure the ship goes... wide variety of specialties available here, as well. Another buncha gold-suiters.
Wha'd I miss? Anything? ((aside from the fact that Loki deleted his post to which this was to be a response.
))