Good for you that you are assuming some responsibilities in your education. Working while attending school is a great way to prepare for the future. I worked while working full-time with three children so I can shed a little light on the subject. First of all, school is the most important factor in all of this; therefore, you have to make sure to have an idea of how many classes you are going to take per semester AND the hours needed to support your studies. Meaning, to achieve good grades, you must put in the time in order to be on point during class and all assignments/exams you have to complete.
So...my advice would be to focus on school during the week. After classes, go to the library or any quiet study area and put in the study/assignment hours which should be at least 2 hours per class. If you have a full load, you need to put in 24 hours of studying per week altogether. In terms of work, please leave that for the weekend. Even if you need to work full-time, you can do so on the weekend. If you separate the work and school work, it will be less overwhelming. Monday - Thursday, focus on school which means the weekend will be free to work and have fun as well.