A little thing I could suggest you (and this works also for drawings and a lot of other media) is to AVOID any detail until you have the main shapes right.
So, even if it could be heartbraking, smooth out the wrinkles, veins and eyebrows, just focus on the shapes of a face (in this case Picard's face).
It's easy to see that you are going in the right direction, it could be a long road (but judging from your progresses, maybe not SO long), but really take all the time you need, ask frequently for advice from other people and as already suggested, take some breaks and use a TON of references.
And another good "tool" is your ability to "visualize" what is not easy to see (like where a bone or a muscle is, etc...)
Keep up the good work
P.S.
Ears are really hard to do (as well as a convincing mouth) so you could "practice" on sculpting a ear alone (separated from the main project) use your ear as reference (taking pictures of course, otherwise it will be a little hard to see it!:lol)
For skin texture and other details there are some resources online (a good tutorial could be found on the "3D & Sculptures" forum on Conceptart.org it's a "sticky" at the top of the page
), but these are the very last steps...
