InTheCrew,
Here is what I look for:
1960d Small Date over Large Date, and two other doubled dies, one showing primarily in "WE" of In God We Trust, and the other on the date
1964
DDR (most notable on the last S in STATES)
1968d
DDR (clearly visible on the FG designers initials)
1969s
DDO (VERY clear, and very valuable!)
1970s Small Date
DDO (clearest on IN GOD WE TRUST)
1971
DDO (IN GOD WE TRUST)
1972
DDO (lots of doubled dies this year, all fun to find, some quite valuable)
1972s
DDO (EXTREMELY RARE, clearest on IN GOD WE TRUST)
1980
DDO (clearest on the date, scarce)
1983
DDR (very clear on all lettering)
1984
DDO (doubled ear, very obvious)
1992 and 1992d CAM (the 92 is scarce, and I believe the 92d is either one or two known)
1996
WAM (unique)
1998
WAM (scarce)
1999
WAM (rare)
2000
WAM (tough to find, but the easiest of the
WAM's)
I also personally look at the reverses of all 94,95,97, and 2001 cents for the possibility of finding another
WAM1994
DDR (two different
DDR's, both different combinations of doubled columns)
1995
DDO (clearest on LIBERTY and IN)
1995d
DDO (scarce, clearest on WE)
1996d with Lathe Lines - no real market established for these as of yet, but they are scarce. These lines are in concentric circles on the obverse of the coin, giving the coin surface a "bullseye" look. I've found about a half dozen of these.
1997
DDO (doubled earlobe)
2001
DDO (mostly visible on the Y of Liberty)
2004
DDR (E PLURIBUS UNUM, look for the dots in the motto to be distended (not round))
2004d
DDR (similar to 2004
DDR)
2006
DDO Lots of doubled dies this year, the most valuable ones show either a doubled earlobe or an almost visible to the naked eye doubling on LIBERTY. Identified on coppercoins.com as 1DO-017, don;t mistake this for a large number of less dramatic doubled Liberty
DDO's
That is a summary of what I look for. See coppercoins.com for many many more varieties and detailed pictures of most of the above; it is an invaluable resource!