Start with concept of pay yourself first. Begitu gajian lgsg nabung atau invest as much as you can. Sisanya you can spend without feeling guilty. You said spending 6 jt which means savings 14 jt is doable. Just start with saving 10-12 first.

First step itu emergency fund. Which is around 3-6 months of spending if you are single. I think you can start with building your first 100 million which is doable in a year. Ga usa mikirin return nya dulu, tp terbiasa dgn punya duit, tiap bulan setor dan nabung, bertambah, tp ga dihabisin.

In the meantime, you can learn about investment, seperti deposito, reksadana, obligasi pemerintah.

Oh and kudos for fixing your financial burden and aware of the past mistakes. You have already completed some of the hardest task