Specialists in coins of the world have so many ways to collect. One of the most popular is topical collecting. Looking for coins depicting animals, flowers, kings and queens, ships, have always been favorites. So many designs, and so many topics...use a little creativity and come up with a really different collection.
How about looking for coins with different languages? Common languages such as English, Spanish, French, Arabic. How about Armenian, Lithuanian, Hindi, Icelandic? Searching for coins with different languages can keep you hunting. Look through "junk boxes" and accumulations of foreign coins. I once saw an exhibit showing fifty different foreign coins, with fifty different languages. Such a collection can be educational, too.
Coats-of-arms appear on many coins. See how many you can find. Australia's coat-of-arms depicts a kangaroo, of course. Bahamas' coat-of-arms shows a flamingo. See what other countries have this motif, and what the details tell you about the countries.
Animals on coins? Specify. Find coins with birds, reptiles, turtles, whatever strikes your fancy.
Some coins depict maps, such as the Euro coins showing a map of Europe. A famous Danish crown has a map of Greenland. There are many more!
Coins struck in different metals and alloys can make a good collection. From silver, bronze, nickel, to stainless steel, brass, aluminum, and some unusual alloys, all in different colors too.
Have fun with your foreign coin collection. Be creative. Think of other topics.