Hi! I’m currently in a very early stage of development of my game. When I started to look forward I found out, I actually need to work on facial animations. Now I expect it to be extremely hard or expensive. Anyone idea to make it for free? All I want to use is simple eye blink and mouth animation when talking (doesnt need to look amazing, but I really want to have it in it)
If you only have very few characters with facial animations, Morph Targets are your way to go.
Morph Targets are Kind of a “snapshot” of Vertex positions on a mesh for example when pronouncing an “O” or smiling.
This way you can animate the face.
If you Need multiple characters with facial animations, a Skeleton face rig is your way to go. The Skeleton is reusable. The con is that you Need to rig the characters to the Skeleton.
Based on what you want to do K.I.S.S. it 
What you want to do is called the talking mail box where the character model goes bla bla bla using a single point of rotation aka jaw bone. Wiring it is simple enough of controlling the rotation using a time line rigged by the need to talk or better still an audio controller that might come along with Epic’s plan improvements to the audio system.
Unless you need some serious hero stuff this is the way most AAA games do it.
P.S. The same goes for the eyes.
Do I need any special software to create these animations or is it possible to make in UE?
No software required and can all be done as a procedural in UE4
Thats great! 
but do I need to prepare my characters for this somehow or… ? I’m using characters from Adobe Fuse, animations from their store…
I don’t know as I don’t have a character from Fuse. Assuming that it can do facial animations then it should have a jaw bone and bones for left and right eyes. If not you fill have to add them and things get a bit more complicated as to doing the set up.
When you export characters from Fuse to Mixamo web site, there is a checkbox to create morph targets, make sure it is checked. Then, when importing into UE4 there is a checkbox to import morph targets, check that as well. Importing a skeletal mesh with morph targets takes extremely long time, but when done you will have a lot of morph targets in your UE4 character that you can use for facial animations. The option to create morph targets will only be there if you import directly from Fuse, it is not available for 3rd party meshes.
Yes, I noticed something you mentioned… thanks for saying it again ! 
definitely helped me