When you want a certain fish:
1. Pick a fishing spot
2. Pick a time of day
3. Pick the appropriate weather
1. *Pick a fishing spot with the best odds for given fish (ff14angler is your friend here indeed)
3. *Or weather change (!)
4. If going big, get a couple of consumables, a lot of bait, get to the place, cast your line a bit before the actual window to learn which fish tugs how hard, use patience if mooching (and stock cordials for rare window changes like that Witchdrop hunt which I do for almost 2 weeks now)... And best of luck!

What? Are you kidding? Oh dear lord! I didn't think I could dislike fishing more. T_T I hear there's stuff about weather too effecting your fishing. Just kill me now.
What's not to like? It's amazing. All of it, bar Fish Eyes and RNG sometimes. Oh, and vague descriptions.
Rest of it is just wonderful. And I mean it. Far far better than botanist or miner, say.