This answer is partly an answer to your questions, and also partly a response to the conversation unfolding in the comments. So I am just going to list a somewhat disconnected list of resources.
One thing I'll say first though is in response to the query "or are they just the polished versions of the results of the last century" made in a comment. As a "stand alone" field, model theory is not even a century old (barely more than half a century by some accounts). So, yes, textbooks such as Marker's book on model theory are relevant for learning about current research. Other good texts are:
A Course in Model Theory, by K. Tent and M. Ziegler
A Course in Model Theory, by B. Poizat
Stable Groups, by B. Poizat
An Introduction to Stability Theory, by A. Pillay
Model Theory, by W. Hodges
Another remark is that, in my opinion, it could be difficult to compile a list of common techniques and "tricks" used in model theory research. Perhaps it's because of how new the field is, and so there hasn't been enough time for such things to congeal. It could also be because a major portion of current research in model theory focuses on applications and interactions with other areas of math, and so the "techniques and tricks" are widely varied.
At any rate, here are more papers, books, and notes. These aren't in any particular order, and certainly this list is incomplete. But I think the list covers a lot, and provides starting points into several active areas. The Forking and Dividing website also has many definitions and examples from model theory with citations.
Notes and survey articles. Survey articles on recent research in model theory can be scarce, but you should look through recent volumes of the Bulletin of Symbolic Logic. That being said, here are some survey-type articles that I like.
a. Stability theory and its variants, by B. Hart
b. Seminar and talk notes by E. Casanovas (you can find many topics of current research).
c. Diophantine geometry from model theory, by T. Scanlon
d. Approximate groups (after Hrushovski, and Breuillard, Green, Tao), by L. van den Dries (more "applied" model theory)
e. Notes on the model theory of finite and pseudo-finite fields, by Z. Chatzidakis
f. Unpublished notes of H. Adler
Papers and books on specific research topics.
a. A Guide to NIP Theories, by P. Simon.
b. Simple Theories, by B. Kim
c. Tame Topology and O-minimal Structures, by L. van den Dries
d. Model Theory of Fields, by D. Marker, M. Messmer, and A. Pillay.
e. Vapnik-Chervonenkis density in some theories without the independence property, I and II, by M. Aschenbrenner, A. Dolich, D. Haskell, D. Macpherson, and S. Starchenko
f. Theories without the tree property of the second kind, by A. Chernikov
g. A geometric introduction to forking and thorn-forking, by H. Adler
h. Model theory for metric structures, by I. Ben Yaacov, A. Bernstein, C. W. Henson, and A. Usvyatsov
i. Topological dynamics of definable group actions, by L. Newelski
Lastly, one can read Classification theory and the number of non-isomorphic models by S. Shelah.