$15000 seem like a lot. But then I have no idea about your financial background, so it could be a small percentage of your wealth. I think it doesn't matter if you invest $1500 or $15, you always need to look into the best way of investing. And try to avoid common mistakes.
I am talking about getting a secure wallet for yourself. Keeping backups of your private keys. Look into how the tax situation for Bitcoin looks like in your country. Compare exchange rates and fees for the different exchanges and brokers where you can buy Bitcoin via, etc.

We have written this guide on the topic on how to invest in Bitcoin for the first time here https://gocryptowise.com/how-to-invest-in-bitcoin-the-beginner-guide/