Ends in 'a' = female: a relatively safe assumption, as far as an assumption here can be safe, with no other context. A strong majority in many places will match that. Many of the exceptions will be obviously foreign names with traditional spelling, which can go either way (may follow that culture's patterns, may not, highly varied).
Ends in vowel (sound) = female: probably mostly true, in that I strongly suspect it's >50%, but it's unreliable enough that I'd avoid trying to base any assumptions off it.
Names really follow no rules at all here. For both good and bad. E.g. most recently I ran across a "La-sia" pronounced "ladashsia". If it's spelled vat-ik'Nff and pronounced "King George" and they're female, then that's what's correct.
Ends in vowel (sound) = female: probably mostly true, in that I strongly suspect it's >50%, but it's unreliable enough that I'd avoid trying to base any assumptions off it.
Names really follow no rules at all here. For both good and bad. E.g. most recently I ran across a "La-sia" pronounced "ladashsia". If it's spelled vat-ik'Nff and pronounced "King George" and they're female, then that's what's correct.