Growing isn't all that easy, theres under/over watering, under/over fertilizing, not enough/too much light or heat, air flow or humidity.
There are also PH levels and Co2 levels but i don't bother to worry about those, at least not yet.
Bottom line is, you can't just stick plants outside in the middle of no where and come back in three months expecting a monumental yield...
I think the most important part is not only knowledge but time and patience. learning to accept and correct the mistakes you make and bettering yourself along the way.
One does not simply go ahead and tell someone they're bad and they should give up, a helpful individual would offer critique or at least some beneficial criticism!
I'd say they're lookin good for where they're at!
Really the lower growth isn't too important as long as the top growth flourishes because your plant will grow to be an easy 3 feet tall, given time!
If leaves dry up and brown at the tips or anywhere, just clip the brow off and leave the green.
The edge you cut won't brown, and they'll give up on the damaged parts and work their energy upwards.
Remember, you never get a better understanding unless you experiment with different methods. I look forward to seeing updates