So far I know HTML, CSS, JavaScript and C++
I've learned most of it on my college course, but I'd say there are plenty of good ways to learn it by yourself.
Really good websites to start with in web development (HTML, CSS, JavaScript) are http://www.w3schools.com and http://www.codeacademy.com. When you study those and get to create a website really useful websites are layoutit.com where you can make outline of the web page by drag and drop principal and copy the html code, and paletton.com where you can experiment with colors and pick colors that go well with each other for your website.
I can't say much about C++ and I'm not that in dept with it yet, but what I found helpful is just experimentation and exploration of various elements, learning what each of them do and how they can be used. Also Youtube tutorials were quite helpful.
And about my preferences, I love working with JavaScript, although it might be quite annoying more than often, it just gives freedom of actions and goes beyond the limit of other web developing languages.
I also like doing CSS sheets since I like designing and styling.
So yea, that was few of my random thoughts, feel free to agree, disagree or correct me.