I like to do my gardening in the Casino or Eltibule by Jesina because both locations have the shortest run between the garden and where I gather water. Generally I find the Casino better because 1) it gets the added bonus of letting me milk cows every hour, and 2) there's no foliage so my plants are easy to see.

Obviously I'll play music for the harvest bonus.

Sometimes I'll use a Garden Display and a Garden Master Potion.

My best tip might be that I zoom in my camera. I get only my stack of flowers/cotton/etc in my immediate view so I can use my "select next item" button and not have to worry about it shuffling in other players stuff.

I also usually save about 200 bottles on the gardening npc so I can make fewer trips to fill up water.

** I'm just curious what the frequent gardeners do to increase effectiveness. Any tips you can share?