Get a spiritual director or a good confessor.
Once you consider doing that, consider this: One advice is looking at things and breaking things down to simpler, more manageable elements.
So. What is masturbation? A sin of the flesh because it is gratifying to the flesh.
So to fight it, take its opposite. Something that does not gratify the flesh. Not just sexually either. We’re talking the flesh in general, e.g.: fasting/abstaining from foods; cold showers (a classic “Go take a cold shower!”

); sleeping with the blanket not covering your left leg and left arm or something; etc.
It is also a sin of selfishness, because
only you benefit from it. Give your body’s abilities as a gift to do good works, e.g.; volunteering to feed the poor, or keeping company to the elderly; cleaning up neighborhoods so people don’t have to feel shame in their community, etc. Work & volunteer so much that by the time you have alone time you are so utterly exhausted you fall asleep (just don’t overdo it and fall asleep and wake up late for important things or, worse, fall asleep at the wheel!

)
Sometimes it can even be a sin of pride, because you think “I’m holy or strong-willed enough to not fall into sin again” and you end up being wrong. Or worse yet you say that you can just confess it later. So, one important thing to do is identify the occasion for sin. Then
avoid that occasion at all costs! This is founded in strong tradition and practiced by many saints as well as being thoroughly used in behavioral psychology.
Also pray. Pray without ceasing. Start living a sacramental life.
These are just ideas, and could definitely lend to trouble without the right spiritual direction. Don’t get sick over it, i.e., don’t walk outside in the winter without a shirt on praying the Rosary to do penance.
Alright now. Good luck!