I wrote out my workflow for a long exposure shot in another post, I hope it is useful:
My workflow for a 10 stop shot is this;
1) Compose, get the shot looking right in the viewfinder, including what I want in the shot and, more often more importantly, excluding what I don't want in shot
2) Focus, then switch to manual focus
3) Meter, with both the camera's internal meter and an external spot meter
4) Expose for a standard shot
5) Apply ND grad filters as necessary to get the exposure right
6) Take a test shot at a short shutter speed
7) Examine the histogram on the short shot for blown highlights or blocked shadows
8) Adapt exposure according to step 7
9) Work out 10 stop shutter speed
10) Close viewfinder to stop light leaking in
11) Check AF on manual and IS turned off
12) Slide 10 stop filter into position checking it covers the entire lens
13) Set the exposure up, either on bulb or with manual setting
14) Check mirror lockup is switched on
15) Lock mirror up, give it a second for any vibrations to die out
16) Set shutter with cable release, either one shot if it is on manual (eg less than 30 second exposure) or lock it off if on bulb.
17) Check top plate exposure timer and also chronograph for exposure time
18) Walk about, try and keep warm for up to 32 minutes!
19) Unlock shutter release when exposure time reached.
20) Review shot and reshoot as necessary (if I am doing a long exposure at dawn or dusk the exposure time is a bit hit and miss as the EV of the scene changes during the exposure).
