Well if you want to make sure that you're
always logging all channels, all chat windows and all query windows you could use this...
on *:OPEN:=: {
.log on $nick
}
on *:OPEN:?:*: {
.log on $nick
}
on *:JOIN:#: {
if ($nick == $me) .log on #
}
~ Edit ~
Paste that code into your script editor (alt+r) under the Remote tab.