I started putting together some writing exercises to familiarise with the Greek letters and learn the correct spelling of the words (e.g. which of η, ι, υ, ει and οι to use for an i sound) a while ago.
Coverage of Duolingo's first section is more or less complete now (it is a little less repetitive though, e.g. where Duolingo uses five examples to teach "and", I may have picked only two).
As you can filter by skill, it may be a useful tool to use along with Duolingo as an absolute beginner.
I tried to add some more pictures because I like learning with images. But obviously it is not possible to properly illustrate most sentences, or abstract nouns. This is why I included German and (partly) Spanish translations, so I don't have to stick with English all the time. It also has the side effect that both alternative languages have e.g. different forms of you so that they can translate some sentences more specifically.
Besides this, I created an illustrated and audio-supported alphabet with the letter names and words (some fruits, a lot of animals, some misc. items) that start with this letter. I created gif animations for this, but now I doubt that this was the best choice.
You can take a look here if you want:
I also included my personal notes about the skills. They are absolutely not supposed to replace the tips, it is more like searching for patterns and structures in what I learn, from a beginner's perspective. I don't know if these could be helpful to anyone else at all, but anyway they are there just in case (and might be expanded in future).
Intermediate: 
Lower intermediate: 
Beginner: 
Absolute beginner: 
A1
(οι γυναίκες διαβάζουν μια εφημερίδα) or 
(ο άντρας τρώει μια φράουλα). Some icons are hard to recognise, and might not be displayed at all on some systems, but it is just supposed to be a visual "anchor" and is not meant to replace listening.