Some players I see use the next finger to trill, So from a C to a C# on the G string they would use index and then middle for the trill. But others simply slide quickly back and forth with the index. I think the second method looks much slicker, more "pro" if you will. But it's harder. I'm trying to incorporate it into my playing. So what do you do? Do you think there's pros and cons to each method?