Things I learned fom my first container garden last year:

No cabbage or brussel sprouts. The cabbage worms ate them down to the
bone.

Fewer tomatos and peppers. Maybe 2 romano tomato, 2 regular size, and
2 pepper plants.

No more strawberries. They take up too much space for too little
yield.

No more sunflowers. Only a handful sprouted, and they only reached
about 18 inches.

No more catnip. The cats didn't really care for it.

I did root crops (carrots, onions) in big mortar tubs. Next time I
will sow the seads in patches and not rows. The rows left a lot of
unused space and needed too much thinning.

Get the lettuce in earlier. Planted it in mid-April and it went to
seed before we had any of it.

The Swiss chard was fantastic, but I couldn't get my wife to cook it,
so I probably won't do it again.

Celery did well, but we didn't eat much of it. Probaby won't do it
again.

Get the spinach in earlier.

Green Globe artichokes didn't produce (they don't until the second
year). I cut the tops and mulched them, but they are in 5-gal plastic
pails and with the cold we've had the root balls may have frozen. If
they don't come back on their own, I won't try them again.