If you have trouble saying "no" when you want to; try some of these:
I'm not comfortable with that
Let me think about that and get back with you
I'll let you know tomorrow
I'll give that careful consideration
I'll give that prayerful consideration
I'm going to have to think about that
Let me give some some thought
I'll take that under consideration
I think I'll pass
I have to decline
I'll look into that
I'm sorry
I wish I could help