The only real problem with that Larth, is if you have grouped with others that have the preflags to request certain quests, you may have already done them, but the quest NPCs won't let you know, 'cause they say you need the prerequisites. With that said, without a log file or check list, that is the best way to go however!
Many quests or series of quests have check lists posted in the comments, and really long often have online check lists on specific guild websites. But without the Quest History or Log file or pre-worked on check list, you'll still be lost on what has been completed out of order.
Yther Ore.