Breaking in to Fishing in Final Fantasy XIV is hard. Fish seem to treat your rod as if it was a crooked leper's finger, and the rare fish that does bite will find your attempt at reeling it in suggestive at best. After a couple of hours of fishing my first attempts
yielded a clam and a piece of kelp.
Read this guide first. If you don't read this, or don't already fish, then what tips I have to give will probably not make sense:
http://www.ffxivcore.com/topic/10378-ma ... o-fishing/
If you don't get a bite after the first 'wait', try a different depth.
Depth does play a role in fishing. Normally when you select 'wait' the fish will nibble first, and then bite on the second wait. However, in some depths fish will bite after the first 'wait.' These spots have always been easier for me to hook a fish. I have had the best luck starting at the very top depth then working my way down.
Once I've found a depth that takes one wait to a bite I will stay at that depth and keep jigging until I hook a fish. Keep trying Master Bait's different 'jig zones' and you will most likely hook a fish. It seems the initial jig has always been substantially easier to hook fish than in a spot where you have to wait longer. This doesn't mean that other depth spots are worthless, but I've always had less look hooking in those spots.
Getting a fish on the line still gets you experience.
Even if you can't catch the fish don't despair; you're still getting experience with each hook. When your fishing rank increases fishing gets substantially easier.
Always use bait -- bloodworms or lugworms for starters.
I don't think fishing is even possible without bait so this should go without saying. If you can get bloodworms I recommend them, but it seems you can only find them by random drop through mining/botany or by buying them for someone's bazaar. Lugworms are available at the fishing guild for cheap--these are your next best bet for beginning fishing.