...based on the rules I've seen so far

Discussion is absolutely welcome. Hopefully we can come to some sort of consensus.

y     = explicitly present
n/non = explicitly absent
mas   = obviously masculine
fem   = obviously feminine
bot   = both masculine and feminine
u/unk = unknown, obscured or ambiguous
 
Genitals? ┬ non ─ [neuter]
          ├ mas ─ Breasts? ┬ y ─ [dickgirl]
          │                ├ n ─ [male]
          │                └ u ─ Body type? ┬ mas ─ [male]
          │                                 ├ fem ─ [dickgirl]
          │                                 └ unk ─ [male]
          ├ fem ─ Breasts? ┬ y ─ [female]
          │                ├ n ┬ Body type? ┬ mas ─ [cuntboy]
          │                └ u ┘            ├ fem ─ [female]
          │                                 └ unk ─ [female]
          ├ bot ─ Breasts? ┬ y ─ [herm]
          │                ├ n ┬ Body type? ┬ mas ─ [maleherm]
          │                └ u ┘            ├ fem ─ [herm]
          │                                 └ unk ─ [herm]
          └ unk ─ Breasts? ┬ y ─ [female]
                           ├ n ┬ Body type? ┬ mas ─ [male]
                           └ u ┘            ├ fem ─ [female]
                                            └ unk ─ [ambiguous_gender]

 
And a link to the wiki entry: howto:tag genders
(Edit by titaniachkt)