Work from the printing, not the character
"Batman" is not an identification — there are hundreds. What separates variants is the printing: torso detail, leg printing, cape material, whether the head is dual-sided, and the exact shade of a moulded piece. Note those before searching.
Check whether it is a collectible series figure
Blind-bag collectible figures form their own numbered series, and Brickonomy lists every series so you can scan a grid of pictures rather than guess a name. If your figure came in a foil bag rather than a set, start there.
Use set appearances to confirm
Once you have a candidate, open its figure page and check the sets it appears in. If none of those sets could plausibly have been in your collection, you probably have a similar variant instead. This cross-check catches most misidentifications.
Photograph a pile at once
For a tub of loose figures, the photo identifier accepts several pictures at a time and returns candidate matches with a confidence level and alternatives. Anything it gets wrong can be corrected by hand before it is saved, so the record stays accurate.