STILL- 1. means that there is no sound or movement 2. on going or continuing
3. still can replace words like but or however.
I like Charlotte, still she makes me nervous

YET- 1. at a future time  2. at the present time 3. like still it can replace words like but
or nevertheless.

Rules of Thumb
1. Use still when there is a period of time covered.
Example: He started when he was five and he still wets his bed. (from then up to now)
2. Use yet when it refers to an instant in time.
Example: The bomb hasn't exploded yet!
3. If still is used at the end of a sentence it refers to quiet or lack of noise, in any
other case you must use yet. Perhaps this reduces ambiguity.
The morning was still. The morning is not over yet.
4. Generally, yet is used after a verb and still before it
Example: I still don't like you. They haven't yet fallen in love.