Any pointers for reading articles digitally (on screen)?
I have terrible eyes and this is a very real problem for me. Although I'm not an eye care specialist I can say anecdotally that there are a few things that have really made all the difference for me. 

First: if you wear glasses, get the computer lenses. Usually they are some kind of an off yellow to cut glare. These really help to reduce eye strain. 

Second: look away from the screen every few minutes. Try to focus on objects away from the screen that let you change your focal distance. I find that doing this for just a few moments at the end of every paragraph really helps. 

EDIT: Use natural light if you can. I've found that turning my desk so that the ambient light from the window illuminates my screen has also helped me a lot. You have to be careful of glare but when I finally got everything situated it made a notable difference. 

Third: media counts a lot. If you're going to use a tablet or eReader look for something that has front/side lighting. Many people like the new Kindle paperwhite but I prefer the Kobo glo. If you're looking for a more stationary solution then I highly recommend a good projector. Prices have come down quite a bit and you can now get an 'OK' projector for just a couple of hundred dollars. It will take a little bit to acclimate yourself to the new reading format but once you do I think you'll find that you like it.  I know that I do.