It´s Mr. Spacey of course! 
Nice start!
Here´s a little theory on why it´s so hard to create good likenesses (I think it´s cruicial to really reeeaaally deeply internalize this in order to develop the right attitude towards learning/practicing… well anything actually… but especially art!):
Our brains are recognition-machines! They try to fill in blancs, recognize incomplete shapes and sounds and scents all day and even at night (sidenote: I´m convinced, that dreams have a lot to do with this). They try to recognize patterns of shade, shape, volume… you get the point. That being said: it´s very easy to make something recognizable, since you only have to do one thing right and your brain will fill in the rest! Therefore we have to rethink what our goal is when creating a likeness!
Is it to make something recognizable? Obviously not, you would have reached it already! I recognized your sculpt very quickly!
Is it maybe to make it very very easy to recognize? Well… that´s better but we both know that´s still not it! We don´t want to be saying “I can very very clearly see it´s him or her, but he or she just has very funky lips here.”
We want everything to look correct. We want to make a copy!
Making a copy in and by itself is not a very artistic, it´s a rather mechanical thing to do, but still we measure the quality of fine art for exemple based on how believable the figures are which we put in all those expressive, dynamic poses! We measure the quality of abstract art in how well the shapes and colors harmonize/how well they capture beautiful patterns that we find in our world.
Therefore the more important question towards being able to create a good likeness (and ultimately beautiful art) is not “do you have the skill to make something easily recognizable?”, but rather “do you have the PATIENCE/ENDURANCE to figure out all the correct proportions?”.
What you want to do is to train your mind in:
-copying angles
-copying curvatures
-copying distances
rather than train it in:
-developing a “feeling for the right shape”.
You will, if you do this, natually develop better feeling for proportions which will make you faster in making the rough estimates but you should never rely on your feeling when it comes to the question “is what I did actually correct?/is it a likeness?”
So there´s good news and bad news. Good news: it´very straight forward! And since it´s so simple, it can be learned INCREDIBLY QUICKLY!
Bad news: It´s going to be incredibly boring, incredibly hard to find the right amount of selfdiscipline to carry on, incredibly frustrating to look for and prepare all the reference you are going to need and it´s going to FEEL LIKE it takes forever and like no progress is being made most of the time!
Whenever you are facing a big task, you want to make sure that you plan/structure your approach in a way that it keeps you motivated the whole way through. Success/achievements/rewards keep us motivated. Therefore you have to find ways to define minigoals/minisuccesses you want to have along the way towards learning to become good at making likenesses.
Nothing can be easier. Here´s my recommendation:
Start with his eyes. That´s your first goal. Create a block of clay, two spheres and sculpt only the eyelids, the bridge of the nose and the browridge on it. Look at the distance between the nose and the iris from the side, the distance between the two eyes, the curvature and angle of the eyelids, and so on. Work at it until everyone you show it to recognizes whose eyes they are. Change the viewport angles constantly/rotate the mesh, change the cameralense width constantly and always look at high resolution reference (you can delete everything around the eyes on your reference to make it even easier). Use lots of reference all the time. The more you do it now, the less you´ll have to do it later. Use the movetool/grabtool and the claybrush only and smooth a lot. Change the size of the brush back and forth a lot! (Regard this as practice. It´s okay to feel like you are bad or slow at it. I always do! But keep in mind: the more you do it, the better you will become, it´s a law of nature)
This will take a long time comparatavely (few days), but the next task will only take half as long, the one after that 1/4 and so on. In no time, you´ll become a sculpting superstar! 
(before next year if you are really determined)
Read this whole post a couple of times over and over, it´s pretty dense!
REMEMBER; our brains are recognition machines, they fill in the blancs! Also they do this when we read. We skip a lot of useful information because it does not appear to be useful or necessary to our minds at that moment!
Little tip: I use bingsearch for searching image references instead of google because it can easily be set up to only show high resolution results and you can flip through the results with the direction keys like you can on artstation. Huge timesaver!
Before I forget: Lieben Gruß nach Stuttgart! 
