Two tickers are all you need. Put 90% in VOO (S&P 500 index fund) and 10% in BND. Rebalance once a year and keep adding every dollar you can spare. This is what Warren Buffet advises should be done with his money after he dies.

Here is a good blog: http://www.mrmoneymustache.com/

He actually puts his money in betterment.com which is another strategy that works.

I've only read german blogs so far, e.g. https://translate.google.de/translate?hl=en&sl=de&u=http://z...

https://www.amazon.co.uk/Guide-Exchange-Traded-Funds-Index/d... is thorough and good (with a UK focus if that's good for you)