A small money management app which really doesn't have a big enough tutorial.
Basically you follow some finanical logic which says the expenses are written off for how long they apply for. Like car insurance is yearly, groceries may be monthly or weekly and snacks and coffee for the single day. It applies a fraction of its cost onto every day until the end, spreading out the expense so these large expenses don't make that day look bad.
Just put in every expense as you pay it, and guess how long it will take. Then after a while the per day expenses level out and you are left with what you earning rate is per day.