300,000 is a great amount to invest if a person has no experience in trading or shares. In my opinion, the best way is the long investment in shares with consultations, if you have no experience in running a business.
If I have this amount, assuming that I don’t trust anyone, I will educate myself in business while doing a feasibility study for any project in my mind. So, if I have 10 ideas, I can do a feasibility study on all of them even if it costs me 10% of the capital. Then work with 20% of the amount for one year, even if I lose or need more funding for the business. I will not use more than 20%, and I can increase the amount or open another with 20% of the current total, and in this way, I will be able to enter 5 businesses or more with a lot of learning, then my earnings will start to double.