Offshore Investing
The rule of thumb generally is to go with the ADRs for convenience sake, unless the average daily volume is less than 10% of the stock's home-market value.
If the trading volume is thin, even a modest order could push up the purchase price in the U.S.. And thinly-traded ADRs also may have a wide bid-ask spread, which means that you buy high and sell low.
Depending on the foreign market involved, you could set up an account with E*Trade or EverBank in order to buy foreign stocks directly in their home market.
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