If you stare at the Thomas Kinkade painting on your wall each day thinking "There's my retirement fund," prepare to pour skim lattes until you're 90. Collecting as a hobby can be a fun, worthwhile and potentially lucrative way to pass time. Amassing collectibles as investments, however, can be a disappointing endeavor yielding nothing but piles of devalued tchotchkes for the next of kin to sort through. The founder of comic book industry bible Wizard, Gareb Shamus, said a year ago that the best advice a collector could heed was to buy what they liked and do their homework. Then...