Whats the best to invest in as a student that earns 40k monthly?

Problem/Goal: Whats the best to invest in as a student that earns 40k monthly that is sure to have profit either short-term or long-Term

Context: So im a Male (19) and currently in first year collage and currently earns 40k a month through online work and I realized I need to be smart on how to save money so I decided to invest my money through out collage. So I decided to do some research.

Previous Attempts: At first I was thinking about buying land/real estate but thats a no go since I needed a huge capital then thats where I found out about Gold investment. I have already thought out a plan to buy ₱20k worth of gold monthly for 12 months which Ill have a total of 240k worth of gold by the end of the year and would probably earn about 50k-60k if I sell it or "prenda" to palawan pawnshops or through online selling. But I think im missing out on better stuffs that I can invest to and im scared because this is my first time and need guidance and insights on what to do and whats the best to invest in btw I think ill pass on online currency/trading stocks any of the online sort since I think it would be risky.