https://www.amazon.com/Random-Walk-Down-Wall-Street/dp/13240...
I wish I had read it already at your age :)
I also like "Are you a stock or a bond".
https://www.amazon.com/Are-You-Stock-Bond-Financial/dp/01331...
2. Retirement investments should be: simple and boring. Once you have a solid financial plan in place that meets those criteria go ahead and gamble with whatever extra money you have if you wish.
3. Read this book cover to cover. It is very boring and very useful. After that read whatever else. https://www.amazon.com/Personal-Finance-Dummies-Eric-Tyson-e...
Be careful about US and GB being rather overweight due to historic accumulation of financial institutions, which only really have an imaginary value not tied to any tangible assets. Thus market-cap weighting gives them a far bigger share of your assets than benefits you in hedging localized economic risk.