I believe that VulnHub is a great resource. It allows you to bring vulnerable machines that others have created into your virtual environment so you can learn more about pentesting. This site has helped me advance tremendously in the cyber world. Having live vulnerable machines that you can practice on in a secure virtual environment, at your own pace, lets you learn many different strategies and vulnerabilities that machines can have. VulnHub boxes are easily imported to virtual machine softwares, like VirtualBox and VMWare. There are many great free resources that I also take advantage of for learning pentesting, but VulnHub is probably my favorite.

VulnHub: https://www.vulnhub.com/