Balcony and roof terrace gardening

Im a new member to this gardening forum website and a product design student looking to pick the brains of those who own and take pride in their balcony/roof terrace garden. I want to know what problems you face trying to make the most of your balcony/roof terrace garden and what things do you feel could make it easier in terms of garden tools, seating and planting etc.
I would love to know your thoughts on this matter.

Many thanks,

Iain