I think there's a lot of differentials when it comes to making a good training routine, the biggest being the individual dog's personality.
When you say he doesn't have a solid sit, down, or heel; what do you mean? That he doesn't obey a high enough percentage of times you give the command? That he doesn't respond fast enough or hold it long enough? Or is it situational (that he doesn't obey in a wide variety of places or distractions)?
Keep in mind that the basic behaviour is easy enough to teach, but that you need to work on each variable separately or you risk moving beyond his capability- which can end up resulting in either giving up, or getting used to not complying. So if he has a basic sit (always include a release so that he knows there is a specific "start" and "stop" to each command) then work on either duration, or speed, or distance, or new situations/ places or increased distraction.
Organize your training sessions to suit Sisko and yourself. I have found that Raffi doesn't like to repeat the same command too many times in a row, and he likes learning new things. So one day I might decide to work on distance for his place command for example. We always start with some attention/ focus to get him in the right mind frame. Then we might do a few easier 'old' commands, like a short sit and a hand touch, then place, then release and brief heel work, then place, recall, place, release and sit-down- sit, touch, place, release and heel work, then maybe a new skill or trick (recently taught him 'step' to put both front paws on a raised surface), back to place, release and sit, touch, then play with his favorite toy.
I try to vary something each time I give a command (once he has learned it to a basic level) so that he generalizes the command/concept- basically that sit means sit no matter which way he or I am facing and no matter where we are or what is around us. Obviously that is a constant work in progress!
Keep in mind to, that baby steps are still progress, especially with the heel. Can you take two steps with him in heel? Awesome! Try to get to three steps, or to move it from the hallway to outside, from the backyard to the front, etc.
You want to challenge him a bit, but still keep it at a level where he can succeed.