To upgrade your watering can without missing a day of watering: on the day you see the weather forecast (on the tv) say it will rain tomorrow, take your can to the smith that same day. He'll have it ready the day after.

And if your having trouble with the fishing mini game, using a controller helps. There's also mods on PC for the game to make it easier.

Villagers birthdays are a great way to boost your friendship with them, even if you give them an item they sorta like, it's a nice jump in hearts