I'm usually using stamina food, depending at my current "age" before starting to farm. Also it certainly helps to be rested.
One trick I use to make sure I can plant things in nice staight lines, is setting up a line of round pole fences along my farming plot.
Using the poles as reference when walking forward (or backwards, doesn't matter in this case) makes it quite easy to keep a straight line.

Another trick I use is planting my next row at the next pole, but the third is dropped right in the middle of the first two rows. By doing so, I slowly create a diagonal line of plants, which makes even more effective use of the space I had.

I've also found out that after you don't need them as food anymore, planting certain crops is a waste of time. Even carrots, although you can feed them to boars. So when moving up the food ladder, do the same with your crops. This makes farming life a lot easier.

As for fishing, as said above, use a karve, sail to a nice spot, paddle at the edge of shallow and deep water and cast your line around 10m from your boat at the deep water side. The moment you see a fish moving fast to your bobber, pay attention, as that's usually a Tuna; which provide you with 4 pieces of fish the moment you catch it. Saves you a lot of time and effort, catching those.

Thorin :)