I have struggled with this my whole life. I have trouble reading my writing, I have trouble keeping track of places to take notes, and then the notes I took. When I was in middleschool I actually wore a small notebook around my neck because otherwise I could not keep track of where and when I needed to be with what (I can't believe noone thought to screen me for ADHD back then :/ )
This past year when I worked 32 hours a week and took my final classes in grad school I got the closest I have ever had to a good system. I use Microsoft OneNote, This is my tool only because I already owned it, I'm not endorsing it over similar systems.
The architecture of the software divides your notes into "notebooks" "sections" and "pages" pages scroll down and can go on as long as you need. I keep one notebook for work, one for school and one for other crap. In each notebook a section for each project at work, each class and each life thing that needs keeping track of. You can sync your notebooks across multiple devices, including mobile devices (though I never did), which lets you read your notes and enter new ones.
The pages work almost like a collage, you can click anywhere and it make a text box where you can type, you can draw you can drop a file into it or an email, or an image. This was great for me because I don't take good linear notes, I write a few words here and arrows and a chart and so on, and so this lets me take notes in the same way I would on paper.
I agree that trying to enter notes on a mobile device is a pain and I have never masted it for more than quick reminders, but you can take a picture of your handwritten notes and upload them. I also found that it made it easy for me to type a note next to that image later in the day, to make sure I knew what it said, or what it was about.
This was the only semester I went to study and actually had notes to do it from. In addition, when I left my co-op in May, I was able to type up notes for my replacement because I had everything saved. The only struggle, like every system, is remembering to use it. I had to set up a time each day to update it with any postits laying around my desk, or any emails I had sent myself with images of notes or whatever, but once I got into the habit, that didn't take much time, way less time than my other searches for "that piece of paper that is in the pocket of whatever dress I was wearing on Tuesday, or was it Wednesday?"