Use the ending conditions
Suppose you have a function reversing a list:
r([H|T])->[T]++r(H);r([])->[].
Since this is the only condition left, this can be golfed into:
r([H|T])->r(T)++[H];r(_)->[].
Or, since this is an identity function:
r([H|T])->r(T)++[H];r(I)->I.
You can also abuse the wild-cards in if statements. E.g.
if A<B->A;true->B end.
This can be golfed into:
if A<B->A;_->B end.