How can I set up an efficient and effective walkspeed / jumppower system?

Now I might make this question sound lazy, but I'm just looking for a start point.

I'm currently working on a project with many walkspeed / jumppower variables like whether a certain ui is open, or if your inventory is overfilled, ect.

All my current attempts at making these systems always have a problem, and that's that they tend to be overwritten by each other, and break. What's the best method I can do this, insuring the speeds will never overlap each other?