Thanks to 
In general it is a good idea to use reference images as much as you can in order to be sure the basic proportions are right. After a quick search using google I found a front and side image of a LEGO Yoda Head.
To have the proportions between the front and side view right I started with adding a sphere and sized the images to fit the shape.
In Edit mode I moved the edges and tried to match them as close as possible to the shape of the front and side image. At this point it is just important to get the basic head shape right.
Firs I deleted the surface on the position where Yoda's ears need to be and than selected all edges and Extruded them out.
I also scaled the ears down towards the end as shown on below gif.
After that I had the rough Yoda head shape ready.
For the eyes I first selected the rectangle surfaces close to the eye position and than used the Transform -> To Sphere command to round it.
After playing a bit with the shape and moving edges back and forth the final eye shape looks like this.
This was the most complicated part and took me longer than anything else. The mouth really determines the whole expression and if it's not right the whole model is useless.
I first deleted the area where the mouth had to be.
Than I added surfaces and shaped it as close the image as possible.
I hope this brief tutorial was helpful. Any feedback on this model is appreciated, specially before I am going to print it this weekend.
Thank you!
