Practive with Score Edit
A short reminder of Part I (Practice with Logical Edit) : I've recorded on a part a free improvisation that a friend played on my keyboard. The part was set to channel 1 in the arrange window and my keyboard also is since when I check the list Editor (Edit/List, Ctrl-G), all notes are showing 1 in the Chn column.
JI'd like to turn this improvisation into a score, starting with my part of channel 1 with all notes on channel 1.
I select the Part. At this stage I make sure I save my work since I know that Score Edit may sometimes crash Cubase and I don't wanna loose my hair ! (I already have lost some since this text is actually version 2 after Cubase had crashed on me while I was writing version 1 ! How much love do I put on this piece of soft to still be bearing this !).
I open the Score editor using menu item Edit/Score (or Ctrl-R). Crashed ? Stay cool! Go to Score/Staff Setting and in Staff Mode select Split. With C3 as splitpoint !
I click OK and I get my score with lower notes on the F clef staff and higher notes on the G clef staff. Notes are still on channel 1, but a voice has been affected to them, either voice 1 or voice 5 (to see which voice a note is relating to, select it and check out the black number in the upper left, right above the score).
The C3 split is only an approximation. Some notes lower than C3 should be played with the right hand and should therefore be displayed on the upper staff (with the G clef). Very simple: I just select these notes on the score, and I hit AltGr-1 (or AltGr-5) to switch their voice from 1 to 5, or vice-versa, therefore moving them from one staff and clef to the next.
If in Staff/Setting and in Staff Mode, instead of 'Split' I chose "Polyphonic' and then click on the Edit button next to it, I'm allowed to display several voices on the same staff, which in certain circumstances makes the score easier to write.
What else to say about the Staff Setting window ?
"Display Quantize" field: I set "Note" to the shortest note value which I want to see appearing on my score. If for instance, I only want whole notes (1), half notes (2), quarter notes (4) and 8th notes (8) to be displayed, but my friend's performance sometimes included very short notes (for instance some 16th notes), setting "Note" to 8 will force Cubase to display them as if they were 8th notes.
This can be further fine tuned with the "Rest" field for minimum rest value to be displayed on the score. Personally I always set "Auto Quantize" to None and I always use "Clean Length".
To enhance the score :
File/Print & Page Setup : allows to set margins. I never use "default value" but instead always "Portrait" and "120 120 100 100".
(Beware, in order for printing to work properly, the printer's spooler must be set to RAW mode and not EMF. Don't ask me why or what !)
To shift to Page mode : Score/Page Mode (instead of Score/Edit Mode).
If I want a Bb to be displayed as a A#, I select it and click on the little button with a "#" symbol.
If I want a C natural to be expressedly displayed as natural, or a Bb to be expressedly displayed as flat, I select it and click on the button with a "?" symbol.
If I don't want this information to be displayed, I click on the "No" button.
If I want to invert the stem's direction for the selected note, I click on the button with two opposite notes.
If I want to link the stems of 2 or 3 8th notes, I select them and easily find the adequate button.
Mind the difference between the arrowed cross 
button and the 
(update) button :
The arrowed cross (to be used rather at the beginning of the work on a score) computes a full graphic layout of the score and cancels some of the settings of your score you might have previously made (distance between lines, legatos, details,...). Whereas UPD only refreshes the screen and is less destructive. Only this button should be used during the fine tuning phase.
Also watch out Hide which... hides the object you had selected, for instance a rest. To make it appear again : Score / Global Settings / Show Invisible, select the Hide word where needed and delete.