Personal finance and investing is another of my big areas of interest. I try to follow the value investing route, as advocated by Benjamin Graham and Warren Buffett. I like to focus on mid-to-large cap dividend-paying stocks of companies with great brands, and try to buy at market dips. I also like to invest in real estate. I'm sure there are more exciting ways to invest, but the conservative approach works for me and matches my personality and risk profile.
Regarding investment books I usually recommend those that focus on fundamentals and mental models, rather than tactics and fads. Saving and investing is as much a matter of building good habits as it is of acquiring theoretical knowledge. A few good books around investing are:
Aside from books, Warren Buffett's Letters to Berkshire Shareholders are also a classic and a must-read.
Finally, I recently came across Naval Ravikant's epic post How To Get Rich (available also in audio format via the same link). Also highly recommended.