Update: I've just got my monthly quota of hits here looking for a walkthrough for the above. I don't want to do that, but I will give some hints.
- The description of each item often has a subtle hint.
- Looking at something after you've used it will occasionally get more information.
- If it's dirty, it probably needs cleaning.
- Some things aren't used to bright light.
- Almost all objects have a different response to the different commands, so just because one doesn't work on something doesn't mean another won't.