I'm student web developer and I'd like to know the things I should know before venturing into WordPress. Where do I start?
Glad your taking the jump into wordpress, wordpress is an amazing platform for developers and non-developers alike, if you have knowledge of PHP, HTML, CSS (and jQuery in some instances) you will enjoy working with wordpress.
A great place to start understanding wordpress would of-course be the wordpress website itself.
I hope this helps, for more specific tutorials and tips / tricks i find myself scouring google every-time i need something.
WordPress Codex is official documentation wiki for the project. It is far from perfect in advanced corners, but basics are covered well.
Since you will need to spend a lot of time in WordPress source, it is best to have it installed and running on your local computer. Any decent Apache-MySQL-PHP stack will do. PHP debugger and good PHP-aware IDE will be more than beneficial.
You can see what typical tools of WordPress developers are in this question - Software for WordPress Theme and Plugin Development?
You can use many of the available tutorials on internet. Use this https://developer.wordpress.org/ and you can be an expert. If you feel hard to follow there are hundrerds of tutorials available. I would suggest the following tutorials.
Please make use of it if you are still helpless