How do I budget myself to zero?

I am so proud of myself for paying off my debt with the help of this sub. I have started to save and invest, my credit score has risen by 100 points, and I have started to learn to live within my means. However, this means I have no money at the end of each month! How do I budget myself to actually have money left over at the end of the month? What are some active tips that I can follow (I'm sorry I am a retail worker and have very little spare time) to find myself with extra money at the end of the month to maybe put towards paying my house off sooner? I have to pay around 3.5k a month and my savings are around 10% of my income (I don't know if that will increase or not).