Timing:

• Aegisub: 100ms = 1tick
• Lead-in: 100-200ms
• Lead-out: ~300-500ms
• When two lines are near each other: Prioritize keeping ~50-100ms for the line you're leading into
• When two people are speaking: I still haven't figured out what's best, but generally: They don't have to start at the same time, but they look better if they end at the same time. Try to keep overlap to a minimum, even if it means ending one of their lines a few hundred milliseconds early.

Shortcuts:

View > Options > Interface > Hotkeys

• General Workflow: audio/commit commits the line and creates a new one if the timed line is the newest line, so you can use G after you've set the lead-out to immensely speed up your timing. Use A and F to scroll left and right, and your mouse to set the lead-in and lead-out timestamps.

• Another useful option is this:

                                            View > Options > General > Audio
  

• It snaps the start/end of lines to the closest ones within a threshold, so you won't have any random overlaps or blinking subs that you didn't intend.