How to find a good cooperator?

After a year of oversea business experience,one question bothers me very much! it is how to find a good cooperator in the European and American market.

During the past year,i have got in touch with many friends,and enjoyed a good beginning,but most failed in the end.

Now anyone who is familiar with the job,and the above market,pls share with me some usefull resource:for example business web populer in these countries, and so on.

Best Wishes to all of you!!!