The first title everyone tends to get is "The Heart of the Party" from commendations after doing dungeons and guildhests. You can see your titles in the Character screen. I just leveled two alts to 50 and they only have the Heart of the Party title. Another common title is the one you get for obtaining relic and is fairly easy to get (just complete the first relic questline). A lot of other titles come from just playing a lot (doing a lot of FATEs, Dungeons, Levequests, killing monsters, leveling multiple jobs to 30, leveling multiple jobs to 50, ect, ect)