Hmmm thats tough to answer since it totally does depend on your level/goals/where the horse is at/how the horse is that day/a million other things-not to mention what you need to work on can change depending on the day or your rides as of late-but it sounds like you know that already :)
As I learn more, or feel like I am backtracking, my routine changes. As of right now I usually start out letting my horse do a stretchy walk/trot to loosen up her back before I ask for any sort of collection-the colder it is outside, the longer this part of our warm up is since my mare has a tendency to have quite a tight back anyways. I also find just focusing on getting her to move forward at this time is very helpful. I also do a few halt/walk, halt/trots to get her listening to my aids. Depending on how she is that day, I have a "conversation" with her at the halt, applying *some* pressure to the reins and giving as soon as she softens her neck even the slightest. I then apply that in the other gaits as need be. It makes it very clear to her what I want and what the reward is.
As I start to move into collected work and get her in frame, I do a number of direction changes through a 20 meter circle to help supple her neck and spine. I'll do a number of voltes as well (10 meter circles) and work on transitions at the end of some of them. I will practice going from a very forward posting trot to an-almost walk sitting trot and back to the forward posting to work on my half-halts and to get her attuned to my seat. I always make sure she's really moving forward and driving with her hindquarters-never riding backwards by pulling on the reins to try and get her into a certain frame.
When I canter, I focus alot on half-halts since Raisin has a tendency to run during it. I use the canter to help develop the trot as well. I try not to just go in circles and not change anything. After I transition to a trot from the canter I usually let her stretch-I dont just drop my reins, I still have contact, but shes in a different frame. This generally makes her more willing to collect more again. Sometimes I'll work on leg-yields down the long-side, a turn on the fore-hand, and a leg-yield back down (or a shoulder-in) but we're really not that far along with our training and I usually do this when my instructor is around to make sure its correct. The turn on the forehand really helps her to round her back and get light.
If the ground poles are out, I'll go over them to get her paying attention to her feet and picking them up.
Like I said though, it really depends :p
Working on a circle makes it easier to frame your horse in, but its important to keep changing what you're doing throughout your workout to an extent to keep him from getting bored. Work on communicating clearly with your aids, be that in the form of transitions, half-halts, etc. and remember to not just go around and around without changing something. Even if you're doing something right, you don't want to overdo it! Transition work is great too.
Regardless of how my workout changes, I make sure that I maintain consistency in it (so if I trot a 20 meter circle to the right, do a trot volte at K, and canter out of it, I make sure I trot a 20 meter circle to the left, do a trot volte to the left at K, and canter out of it.) I want to make sure I am working both sides of my horse evenly. Sometimes its tempting to neglect one side, since every horse/rider has that not-so-hot direction, but I think its really important to keep your ride balanced both ways. I also make sure to keep my geometry as accurate as possible-its make a big difference for me. If my mare manages to push out or fall in on our circle, she'll break gait.
Ok sorry for the novel...that's kind of my ride in a nutshell right now. Enjoy your guy, and have fun learning!