Strategies to remember papers that you read What strategies do you use to remember papers that you read? 
I usually take notes, but when after a while I look at the notes, I don't remember most of the details. So I have to go back to the original paper and read many sections once again. 
Are there better strategies for remembering key points from papers you read for a longer time? I am mostly talking about CS and Math papers in which details can be very easily forgotten.
The advice I was given by my supervisor is to write about a paragraph on each of the four following points for each paper you read (note, this is from a very CS perspective):


What's the context for the paper, in other words, what is the issue that the paper's trying to tackle, and what's the prior work in the area, or the work that the paper's trying to build off. For word published as parts of bigger projects, what's the overall aim of the project, and how does the paper fit in. 
What's the key contribution of the paper, i.e. what is the central idea, or improvement that the paper presents over the state of the art. I (personally) find this one of the more important sections (especially in terms of remembering papers later), as this is where you need to really hone in on what the code idea behind the paper is, without all the extraneous implementation detail/proofs/arguments.
Criticisms of the work, no research is perfect! I'm personally terrible at looking back at papers I've read with rose tinted glasses, leading to a little bit of imposter syndrome. Having a list of criticisms of the paper can help to dull that, as well as providing a good counterbalance to the "key contribution" section.
Any other thoughts. As the purposes of the four points is to help remember the paper later, it's also important to make a note of what you personally thought while reading the paper. Really liked a sidenote they made? Make a note of it. Found an corner case you don't think they cover properly? Make a note of it - you could turn it into research later! 


I usually find that I take about 10 minutes writing notes on each paper, along with about the amount of text that I've written for this answer. Your mileage as to how much you want to say about each paper may vary however.