Ideally, I always imagine that I'm inside of the giantess' room unaware.
I imagine being a tiny man stuck in any other situation (outside of a building, in a random city) would be extremely terrifying. Trying to avoid the massive footsteps on a busy sidewalk, or avoiding massive puddles of water would be difficult, as well as dealing with the temperature (assuming it's not summer). I think it would be similar to how insects approach the outside world in real life; sneaking into homes at any chance in order to hide and avoid death from nature.
This considered, I imagine I would be very afraid within this girl's home, and try to avoid being noticed as much as possible. I would hide until night time and search the kitchen floor for crushed scraps of food, and try my best to avoid predators (larger insects, pets). That's only if this were completely real, though. I know my behavior would be a lot more risky within my fantasy, considering I can reach the girl's bedroom to hide there. That brings up an interesting point, though - do you usually imagine a situation in which there is hope for growth again? I always imagine that the situation is hopeless, and my subsequent behavior gets me killed. If there were no end in sight, I would lose sexual inhibition and worship her more often, doing what I can with discarded socks/underwear/tshirts/jeans/shoes/hair accessories/makeup/food/trash. Basically going as long as I could with no limits. I would try to make it to her socks as often as I could, licking and sniffing and masturbating while I hear her footsteps or voice. Ideally, I'd die by my own mistake; masturbating deep inside of a sock left on the floor until I pass out inside with the smell choking me. Eventually, she would either put me back on and crush me, or (more likely) drop me into the hamper (at speeds and strength which I'm not designed to handle) with other dirty clothes to die a humiliated, asphyxiated and dark death with broken bones.