How do I play this exactly? Sanity/Light and Darkness - please explain

[Tintin]

I'm enjoying the game but finding it to be a little frustrating. I've played stealth games before (the Thief series are brilliant) and I've played the Penumbra games (also very good , so I'm not exactly expecting to be invincible. I also love the idea of having a Sanity bar that needs to be monitored but in all of this Daniel still comes across as a real pansy. I'm creeped out by a lot of stuff but he seems to freak out often at absolutely nothing. Any tips on how to stay sane? My oil lamp runs out quickly and using the tinderboxes seems a bit strange and a waste of resources when I'm in the area for such a short time. I'm not sure how this works. Obviously Daniel is comforted by the light but it also makes it easy for the enemy to see him. Obviously he hates the dark but why then does his night-vision activate only sometimes? What makes some darkness less frightening then other patches of darkness? And why does it often get darker as you move closer to something; shouldn't his eyes adjust to the darkness? Someone please explain this all to me.

(I'm up to the part where I've found the four chemicals and combined them to make Acid - interesting).

Thanks guys!