Typical collectors start out collecting a variety of coins — often anything that catches their fancy — and then decide on a favorite denomination, type or series.

Among the most popular sets are Lincoln, Wheat cents, Indian Head 5-cent coins, Winged Liberty Head dimes, State quarter dollars, Morgan silver dollars and American Eagle silver bullion coins.

Rather than immerse myself in collecting entire sets, or in assembling the best affordable type or date sets, I decided to look into semi-key- and key-date coins of various denominations and series.

I switched to semi-key- and key date coins rather than spend my limited hobby budget on new collections or on upgrading existing ones in my set registries.

You probably have a lifelong passion for certain denominations, varieties or series. Mine are deep mirror prooflike Morgan dollars and rainbow-toned silver American Eagles. I’ll always collect those. I do like other series, but not enough to invest the time and money to collect a complete set.

But at this phase in the hobby, after collecting now for a half century, I wanted to expose myself to different denominations and types, as well as holdered examples of some coins parallel to my raw collections.

For instance, I have a complete Lincoln, Wheat cent collection in a Dansco folder. But I don’t have a holdered set of Wheat cents, which includes too many common coins. So I focused on these key dates in Professional Coin Grading Service and Numismatic Guaranty Corp. encapsulations: 1909-S V.D.B., 1909-S, 1914-D, the No D version of 1922-D, 1931-S and 1955 Doubled Die.

I also have acquired or am in the process of acquiring holdered semi-key- and key-date Indian Head cents (1872, 1877, 1908-S, 1909-S), Liberty Head 5-cent coins (1885, 1886, 1912-S), 2-cent pieces (1864 Small Motto, 1867 Doubled Die Obverse, 1871, 1872), Winged Liberty Head dimes (1916-D, 1919-D, 1919-S, 1942/1, 1942/41-D), Washington quarter dollars (1932-D, 1932-S) and Walking Liberty half dollars (1916-S, 1917-S Obverse Mint mark, 1919-D, 1921, 1921-D, 1921-S, 1938-D and 1941-S).

Focusing on semi-key- and key-date coins opens a learning opportunity. You study the history of our hobby from a design as well as rarity perspective. You encounter series in which you previously took no interest, and that now may rekindle new hobby passion.

A lifelong journey in numismatics takes several routes and trajectories. Which one are you on at the moment?

Michael Bugeja, a coin collector since childhood, is a professor at Iowa State University and also a member of the Citizens Coinage Advisory Committee. He is a nationally known author, journalist and educator.