I have got a fixed focus, 5 MP camera with 3.3mm focal length (not sure what it means) on my phone. I want to know what's the best way to take pictures with since it's missing auto-focus feature. Is it worth for taking landscape, close-up pictures?
IMHO the best and only way to take pictures with such camera is to point and shoot. You don’t need autofocus since the camera construction means that practically everything on the photo will be in focus, be it a landscape or a close-up (or both at the same time). The good thing is that you don’t have to do anything special to get the photo, the bad thing is that you can’t do anything special to get a better or different-looking photo (except post-processing).
Regarding the focal length: There are two ways to get an object into focus. The first one is by determining the distance of the object from the lens and setting an appropriate focal point on the lens. The second one, used by fixed-focus lenses, is to focus the lens on a fixed point close to the lens (the hyperfocal distance) which gives you an infinite depth of field. Then all objects are in focus no matter their distance.
I’m not sure if the particular focal length number given for your lens says much. If your camera has a 1/6" sensor, the 3.3mm focal length would be something like 46mm in the 35mm standard.
PS. Hopefully I got everything right, otherwise I’m sure there are enough knowledgeable people to spank me.