This maybe a little bit queer but FOR ME it works!
How it works: First i dont got a APP! i got a little paper notebook and when i got a Task i dont write down:"make the CSS work better". I Write:"How can you make the css better?". Mostly the questions are tighter and more to the point but this is just an example. I use diffrent Colors too ! Black/Blue just to write it down Red/Green/Orange/etc. for things that let me later know what i thought that moment. I Carry that thing always with me! ALWAYS! Maybe a Solution for a problem comes in my mind when iam at the Metro or on the Street.
Why i do that? I dont like Tasks! Tasks always have this: you MUST do that and that... baaah NO I dont like it.
Really DONT use a APP! Wunderlist, the milk thing, evernote etc. are ALL good app's but the just all take to long!
Maybe this will change with a Touchscreen and pen but i like my paper notebook :)