Andrew Chen's blog is probably the most relied source when it comes to learning about metrics like CAC and LTV. For real life case studies, follow Nathan Latka's podcast to know what each of these mean for different startups in different industries.
Growth Hacking is ever evolving and hence what worked in the past may not work in the future. But they are still good resources to learn about what worked in the past. Two books that I can recommend are:
1. Viral Loop
2. Traction

You can ask me any follow up questions that you may have.

The best place to learn is priceintelligently.com

They've done a lot of work on their blog explaining key metrics and helping SaaS companies grow through data driven experiments.

As far as growth hacking, I highly recommend the following:

- Learn how to write well - read On Writing Well - Writing is your analog attack vector for anybody doing growth.

- Participate in online forums that interest you. You need to naturally make it part of your DNA understanding how forums work, feeling the highs, the lows, the no traffic, the high traffic, etc... get obsessed.

- Learn APIs, how they work, and regularly browse sites like Producthunt.com and betalist.com to learn about new products. WHen you see them, try to imagine how they were built and upon which APIs they were constructed.

- Scraping & Crawling - learn the game bit.ly/scrapingmonster

- Build Automation bots leveraging zapier initially, and as you get more advanced, learn the capabilities of tools like ubotstudio.