I recommend basically reading books by:
Peter Lynch, Phil Fischer, and then chapters 8 and 20 of the Intelligent Investor. The book, Applied Value Investing, is also a pretty good place to start that actually does a lot of things well, combining both theory with practical case studies. -Reading the Buffett Partnership letters (not the Berkshire letters) is very helpful for someone managing small sums of capital, say below $10M
In addition, you need to read and learn about financial accounting and valuation. John Tracy's How to Read a Financial Report is a good starter... for valuation Aswath Damodaran has a pretty good book that can be combined with McKinsey's book on the subject. Beyond that, some more advanced accounting books, especially forensic stuff is great to know. Financial Shenanigans and Creative Cash Flow Reporting are where I'd start with that.
To be really good you also need to read quite a bit about psychology/mental models. Look for speeches/lectures by Charlie Munger. Books like Stock Market Wizards/anything that contains a ton of interviews with investors are also great. Reminisces of a Stock Operator is pretty good for giving you an account of the ups and downs that come with investing -- the guy the book is based off of blew his brains out. Studying financial history is also a must, especially with learning about prior bubbles.
Finally, you just have to commit to reading a whole lot, every day, and becoming a learning machine.