I have created a list of all of my responsibilities within each position, all of the goals I need to achieve and schedule when I do them by (for example, send out customer statements before payday).
Once I can see the details laid out in front of me in my lists, I then plan the stepping stones to achieving those goals.
In my calendar I have set days and times to commit to various responsibilities, but I also create a daily to do list to help me break-up the goals into manageable smaller steps to ensure I am achieving the end result.
I have to split my attention between my positions because I am the only customer services worker for my two small businesses, so dividing my attention across emails and phone calls can not be helped or controlled.
What I can control is how I structure my day in between all of the disruptions to ensure my businesses are receiving the attention they require.
Hope this helps!