Choosing International investments?

I would like to allocate part of my investments into international stocks.

I won't be familiar with most of the companies invested in. And I don't trust an index fund to accurately represent the entire world economy.

In the past I have tried a few mutual funds based on their past performance, but they mostly flopped. What else can I consider in order to choose a good fund?

Or has the world market just been stuck in a rut for years so that any fund would have performed poorly?