I love RTEC post above.Written from miles in the trench just doing it...we all know this.
I submit some further thoughts,as this is very dear to my heart,and I think is a fundamental building block of scoring.Especially comedy,which I love to hate ,and hate to work on,but enjoy when done to satisfaction.
First thing is to think about where the cue should maybe start and end.It tends to frame your thinking about what the music arc will be like inside that sequence.You might want to go through the sequence and put markers at anything that "might" be a candidate for a hit point,or sync point to your music.As I go through it once,I get the feeling for tempo as well,and the correct tempo will tend to hit alot of those markers fairly well.That's when you know you've got into the same groove as the video editor.Nevermind the temp music,unless your video editor and director has annointed it as very close to correct.I've gotten nailed getting too close to the temp in terms of hit points and tempo far too often,frankly,these days,I enjoy pushing off the temp early on,just to refresh my thinking once I've understood what the temp brought to the sequence in the first place.
Once again,you should think about music arc inside this sequence,where is the possible climax point,if any,and what might be a good ebb and flow.You can start to think about how to get to that highest intensity moment,as THAT moment should be in sync with the image in some form,at least as far as the emotion is concerned,be it a moment of epiphany ,or triumph or absolute failure or major plot point.Whatever pushes the moment higher.
Once you are fairly certain you have your hit points lined up,you can then get into the details of lining up the important ones by using micro tempo adjustments.I'll try and do these over as large a sequence area as possible,mostly to avoid large tempo moves if possible.I also will use signature changes to line up points that need to be on the "one",no matter where they happen to be sitting at the current signature.So for instance,I"ll throw up a 2/4 bar ,assuming I'm in common time,if I want to start a new 4/4 after two beats.Or sometimes even more altered,such as one bar of 5/4 and adjust the music so the more important beat "one" of the new hit point is BANG on.It's amazing how much you can mold music tempo-wise and play with adding or subtracting a few measures without the audience being aware of the manipulation.It works best if the music supports the dialog,as in adding the pauses,or taking them out to sync around the words.Take for example lines like in the Terminator "I'll be back",I'd step aside for stuff like that,and the audience would forever forgive me the manipulation,they would most certainly welcome the hole I created.
Somewhere in all this,the time you take upfront to set up your roadmap will pay you dividends later.A very well laid out sequence ,even with drastic tempo and signature changes,where major hit points are exactingly located and accounted for,and the score should practically write itself from that point on.
One cue I recently wrote involved me setting up my hitpoints.This sequence had three different bad guys in a fight scene that was bonkers.Without really having an idea of how to write the music,I set out to map out the hit points,and loosely play with tempo options.Well by the end,I had some squences at 6/8,some specific ones at 5/8,and one middle section at 11/8.I thought I'd written myself into a complete corner,but decided i'd try my hand at my whacky roadmap.After some soul searching and thoughts about movement and flow,I ended up realizing the changes invited key changes and ended up winning the day.I used the 11/8 as 3+3+3+2,and it created a nice tension that anyone would pick up on,just being any odd meter tends to sound unresolved(at least to me).It also created a pause in the sequence that I would never have thought of had the signature change not occurred.The end result was that the changes in tempo(slight) and signature(large) created a kind of synergy with the action that wouldn't have been obvious had I not taken the time before hand and mapped out some plan.The rest was just filling in the blanks.
So much to learn,so much to still explore,but at least with some kind of approach,you can get productive,rather then stabbing wildly in the dark for some kind of "idea" that might win the day on that sequence .
Structure tends to invite creativity,as it limits your options and gives boundaries.