We usually switch at the outstations, so that the takeoffs and landings are at least somewhat varied. Some Captains will want to fly first, some will want you to fly first and still more just don't care.
There are a few things that Captains MUST do (e.g. landing at certain airports like Inyokern, when we still went there, or Flaps 45 instrument approaches in IFR conditions), and we usually consider that before getting under way.
So, FO >(crappy weather) preflight>security?>preflight>FMS
Captain>paperwork, briefing
The typical sequence for FOs on my airplane is:
- get to airplane
- stow your stuff
- do walkaround
- build nest (charts, headset, old-man ass pad as applicable)
- Safety Check items (oxygen mask, emergency equipment, aircraft documents)
- Check for al-Qaeda, guns, bombs, illegal immigrants and @
DPApilot (security)
- Airworthiness check (in aircraft's maintenance can - not flying with an open write-up)
- AFIS, FMS entries, clearance, ATIS, performance (max takeoff weight), etc., to fill in the takeoff/landing data card.
- Read Originating Check
- Follow the Captain through on the weight and balance and when your numbers agree, compute takeoff data (speeds, takeoff torque)
- Briefings (takeoff and FA briefings)
- Pre-start, Engine Start checks
- be gone.
That's the general flow. Both crewmembers are responsible (with the Captain of course bearing final authority/responsibility) for airworthiness and preflight tasks.
The Captain, meanwhile:
- get to airplane
- stow stuff
- Safety check (power on, APU start in addition to all the other interior preflight and security items)
- Originating check (it can be long, or longer if the first flight of the day)
- build nest
- Read release and think great Captain thoughts about this leg (or sit there doing nothing with a vacant or peeved look on his face wondering why you aren't done with the walkaround yet)
- Manual manifest (W&B)
- Briefings
- Checklists
- Go fly
If you're lucky, you'll get to trade off walkarounds and such.