I tend to write as I play, which is partly why it takes me so long to do an AAR. I know, it's not the most efficient way of doing things...
Generally, when I get to an event I think would be interesting, I will CTRL+Print Screen then paste it into word, crop it/edit it accordingly, write my passage for it in the forum, add the pic and then continue playing, repeat as required. On occasion I will save a word doc with some flavour text and screenshot to write it up afterwards, particularly if I'm exploring something a bit interesting that could swing either way/make me revert to an earlier save (such as opening the L-gate and unleashing death upon everyone...).
As I say, it is not the most efficient and does take away from the gameplay a little bit. I'll probably look at doing something similar to what others have suggested here
Generally, when I get to an event I think would be interesting, I will CTRL+Print Screen then paste it into word, crop it/edit it accordingly, write my passage for it in the forum, add the pic and then continue playing, repeat as required. On occasion I will save a word doc with some flavour text and screenshot to write it up afterwards, particularly if I'm exploring something a bit interesting that could swing either way/make me revert to an earlier save (such as opening the L-gate and unleashing death upon everyone...).
As I say, it is not the most efficient and does take away from the gameplay a little bit. I'll probably look at doing something similar to what others have suggested here