So I generally budget for food, car maintenance/insurance, gas, yearly parking cost from the school 😡, utilities which are not included in rent, any pet medical expenses, any eating out which I separate from food to track how much I'm spending because I can't help myself with that In-N-Out, cell phone, cable/internet/netflix, household supplies like TP or paper towels or clothes, any bills for medical insurance/doctor's appointments, and a little spending money every month. I also have an emergency fund that I don't touch unless there's you know an emergency.
When you're first starting you also need to consider school supplies, club dues, rabies vaccine and moving expenses. There's also a thread called Expenses During Vet School you might want to check out.