Sometimes new collectors ask, "What should I collect?" The answer I would always give them is "Collect what you like". If you like complete sets, build one of those, if you like RPM's and Doubled Dies, collect those. If your interested in investing in Lincolns here is my advice on Key dates, varieties, complete sets and high grade coins:

Key Dates. Key dates have always been and will continue to be the most solid investment you can make. Key Date prices continually rise, and will continue to rise.

High grade cents. In my opinion high grade cents can be a risky proposition, especially if you are buying uncertified examples. If you collect High Grade cents I would stick to PCGS and NGC certified cents. Also, view population reports and make yourself well versed in the populations of each grade. Registry sets have made "top population" cents very lucrative.

Varieties. Most Varieties are not good investments. Popular varieties like the 1955, 1972 and 1983 doubled dies have a high demand and popularity, and are solid investments. More obscure varieties like the 1960 D rpm 19 and 1972 ddo 6 do not have much potential for growth. Furthermore, most coin dealers and collectors are not well versed in these more obscure varieties and have no interest in them. If you like RPM and DDOs, collect them. If you are investing in these varieties, stick to the more popular ones like 1944 d/s omm1 and 1956 d/d rpm 8.

Complete Sets. Here is a rule that new beginners are often not aware of: "A set is never worth more than the sum of its parts". Most dealers and collectors will only look at the key dates and semi-keys when purchasing a complete set. Do not think that having a complete set will make your coins more attractive to collectors and dealers. Most dealers and collectors already have the common coins and are only interested in the "keys".

To summarize, key dates are the best investment. The key date Lincolns are the 1909 SVDB, 1909 S, 1914 D and the 1931 S. Popular varieties like the 1922 plain, 1955 ddo 1, and 1970 S small date are good investments, but obscure varieties like the 1957 D rpm 3 are not. Complete sets are not worth more than the individual coin prices. High Grade coins have questionable economic futures. If you are investing in high grade cents, stick to PCGS and NGC certified cents because of registry set value.

This is just my advice. I would like to hear your thoughts as well.