The key part of the inventions process is identifying need. And the key way to do this is to pay close attention to your own and other peoples' lives. Just off the top of my head, two needs occur to me, based on two of my pet hates: changing the bin; and having to stand up (particularly in queues).
Putting out the rubbish. It's a pain. If you do it the night before the bin men come, then foxes tear it open leaving a mess. If you put it out in the morning, it adds to the mornings woes (don't get me started on mornings). My first thought on solving the problem is some kind of chute from the kitchen to an outside place where the binmen would collect it. This way, rubbish is never stored in the house and I wouldn't need to do any changing. The problem is that the nature of kitchen waste means that chute's going to get messy. Really messy. Next thought: a robot. This is a particularly high-tech solution to a low-tech problem. A humanoid robot would do the trick, so perhaps would some kind of chair-lift like rail that carries the bag outside, tying it in the process.
Another alternative would be to do away with bags: they add to the landfill after all. A bin hatch would be built into the side of the house and rubbish/recycling would be dumped straight into a set of bins (see diagram). These would be picked up and emptied by the bin lorry, perhaps with some kind of robot arm that swept the inside of the bin (and sprayed with water to clean).
With respect to my issue of standing, the absence of queues would be a nice start, together with much more public seating. In lieu of this, what I need is a seat I can carry with me. It needs to fold so I can put it in my bag. I've seen umbrella seats, but how can the length be folded? Using a combination of locking corner joints (as used on step ladders) and telescopic arms (see diagram). Obviously a seat would need to be attached at one end, an either a spike or piece of rubber on the other.