I have two lists i review everyday The first list are those things that i absolutely have to get done that day. I may include tasks that i do everyday if sometimrs i have trouble completing them. It feels good to check them off. If there is nothing that has to be done that day i list the three tasks that are the highest priority. If I finish all the tasks on my first list, then i go to my second list and add the next priority task. The second list is a list of all the other tasks i need/want to get done. I am constantly adding items to my second list as things come up during the day. I review this list everyday and move items to my first list as their priority increases. If I find there are tasks that im never getting to, i either assign a date to them or i pick a day to work on all those longterm non urgent tasks.
It depends on how I am feeling in the morning and what I am doing. If I am working, just three things. If I am not working, maybe more. The important thing, for me, is not to put too much pressure on myself, and not to be unkind to myself if I don't get everything done.