to keep an agenda, an electronic organizer or notebook handy to jot down ideas   

I have a daily planner, it helps me stay on track, some people can just remember stuff in there head, I am not one of those people. It helps me pay my bills on time and it really and truly keeps my life on track.

No it's pointless keepin a note book when there is a piece of paper that will do a better job and cant break down on you everytime you write a sentence, Thanks

Yes, even I do that at times. It is difficult to remember all the things, esp. if you are in a meeting. So, jotting it down doesn't hurt;)

Many years, in the month of December somebody gives me an agenda as a present. I like it because I think that it's a nice gift for Christmas and it's very useful. So, I start to use it a lot at the beginning of the following year. But soon, I realize that I don't have so many things to write in it and normally about March I have already forgotten my agenda until the next one.
Generally, when I have to remember something important I either write it in a paper and I put it in a visible place or I jot it down in a big calendar that I have.