So being pretty well signed up to all things Android (I did have an iPhone once, didn't really get on with it), I thought I'd share what I'd call essential tools which have almost allowed me to eliminate paper from my life.
I've run an electronic diary since the days of the Palm Pilot, but that was always as vulnerable to being lost as an old paper one. So Android's native sync with Google Calendar is pretty cool. Anything I add or change on my phone or tablet is automatically synchronised with Google's cloud. And I have a plug in for Mozilla Thunderbird on my laptop to ensure it syncs there as well.
That also goes for Google Contacts, whatever I add on any device is automatically on the rest.
The real killer app for me though has been Google Keep. I've spent years trying to find a simple notetaking app that syncs anywhere, and this is it. It is text and attached photos only (although I have a draw app which can be used to add sketches*), but with Google Keyboard's awesome swipe-to-type feature my Nexus 7 tablet is as quick as a paper notepad. And I get colour coded notes and a powerful search facility, so when I want to find all notes relating to a certain client I just type in their name. Keep syncs to the Google Drive 'Keep' app in the background without any user intervention, so I can view my notes in my web browser on my PC. Being able to email notes quickly to colleagues or clients, or copy-paste them into documents is a massive timesaver too.
Since I seem to have let Google run my life (more on the pros and cons of that another time...), I looked for a way of using Google Tasks for my to do list. Now, the thing about Google Tasks (and there is a basic Tasks app as well) is that each of your to do lists (e.g. work, finances, home, sports etc) is separate. So I found a very powerful Android app called Taskary, which not only combines your upcoming due tasks into a single list, but also pulls in your calendar to give you a single agenda view.
The result of all this is that I now have two mobile devices (the phone for quick reference and quick notes that's always with me, the tablet with its larger screen when I want to do something more heavy duty) that completely replace the notebooks I used to carry around with me. And if I lose either, it's a pain because I have to buy a new one, but I don't lose any of that vital data.
*While finding the links for this post, I came across an app called 'Sketch for Keep', which I'll definitely be investigating!