Do not use as ambiguously, so that it could indicate either time or cause.
An example of what I mean:
(Ambiguous:) As I was talking, my wife left the room.
(Clearly time:) While I was talking, my wife left the room.
(Clearly cause:) Because I was talking, my soon-to-be ex-wife left the room.
This is not to say you should never use as, just when you do choose to use it make sure it is clear to time or cause.
(Clearly time:) As I lay sleeping, someone stole my wallet.
(Clearly cause:) As I was very late, I took a short cut through the park.
A word of caution: If you find that you are using as a lot, you may want to find another word and change it up a bit.
Another point you to keep in mind: Do not us as, as if, or as though to introduce an object or predicate noun clause after verbs of thinking, saying, or feeling. Use that.
(wrong) It seems to me as if that's a great deal of ice cream for such a small a boy.
(correct) It seems to me (substitute I think) that that's a great deal of ice cream for such a small a boy.
Besides the fact that there's never too much ice cream, that that's a great...a boy is the predicate noun of seems.
(wrong) Mother doesn't feel as though she should go to the party without her invitation.
(correct) Mother doesn't feel that she should go to the party without her invitation.
That she should go without her invitation is the object of doesn't feel.
A word of caution: In today's writing society, be mindful of using the word that too often. It could become another trap.