Drawing and painting skills used to be passed down from master to apprentice throughout the centuries. Students were thoroughly trained by drawing first from plaster casts and sculptures, next by copying the works of great masters, and finally moving to the live model. Today's art students are hard pressed to find a school that will teach good foundational skills before expecting them to churn out original concepts. But, for a person with a mind to learn the skills of the great masters, there are great resources out there:
1) Take a class at an atelier! If you're lucky enough to live in or near a major city, chances are you live near a workshop taught by one of the rare few descendants of the atelier/academy system. Nothing beats experience with a live model and a live instructor that can point out how to improve your work during the process. There is a list of recommended ateliers, schools, and classes at the Art Renewal Center website: http://www.artrenewal.org/pages/ateliers.php
I've had a very good experience taking a couple of classes at Gage Academy of Art in Seattle, WA. This school is affiliated with the Aristides Classical Atelier. (Also, any book by Juliette Aristides is a great read.)
2) Learn some anatomy! As wonderful as it is to be able to take a good figure drawing class, sometimes the vocabulary words can come flying fast and furious at a time when you're trying to use the right side of your brain for visual problem solving. It's really helpful to supplement drawing experience with good old-fasioned memorization of important muscle groups and bone structures. Parts of the skeleton stick out as permanent "landmarks" on the body which can help you understand the weight and motion of the body and how to place other related features.
If you want to learn anatomy the way the great masters did, pick up a copy of "Albinus on Anatomy" co-authored by Robert Beverly Hale. It's full of 18th century anatomical engravings. Also highly recommended is "Artistic Anatomy" by Dr. Paul Richer, translated by Robert Beverly Hale, one of the best anatomy resources available to 19th century artists.
3) Take lessons from great masters in books! One of the important components of a classical drawing education is making master copies...that is, copying the works of great masters to understand how they saw things and solved problems. A great way to do this is to grab a sketch book and an oversize library book and have at it. If you want to save yourself some research time, find a copy of "Drawing Lessons from the Great Masters" by Hale (again). Another very popular resource that many artists studied during the academic period is the Charles Bargue Drawing Course. Bargue's course involves copying various exercises and drawings. I did a few for homework in my portrait drawing class and I found it to be a lot of fun! A Bargue book can be pretty expensive, but I've seen a few pdf versions floating around on the web for free (which I don't feel bad about since Bargue has been dead for more than a century). I'm not responsible for any computer virus you may accidentally download; just remember to use a good virus scanner on the file before opening it just in case.
4) Go to a museum! If possible, bring your sketchbook and and make master copies there.
5) Get good at finding used books! As a busy mom, my schedule doesn't permit me the leisure time to go to an art museum by myself during the day to spend time sketching, so I'm mostly dependent on methods 2 and 3. To cope with the fact that art books are usually crazy expensive I try to exercise some creativity:
a) I take regular trips to the library with my toddler, so I'm able to check out one or two books (I can't carry too many of the kind I need at once) and then we go have "story time" in the children's section. Even better than scouring the random selection on the shelves, if your local library is connected to a city-wide system, figure out how to request specific books from other branches! I found a lot of great M.C. Escher books that way. The best part about this is that you can give the books back when you're done so they don't just take up space. It is handy to have a few reference books at home permanently though, in which case...
b) I used to live near a used book store that kept a great stock of art books for very inexpensive. I like paying less than $10 for something that would cost $50+ on Amazon while supporting a local business.
c) Sometimes I scan the book sections in my local thrift stores. I found a copy of Hale's "Drawing Lessons from the Great Masters" for $6 at Goodwill. It smelled like somebody's basement at first, but was otherwise very usable. It was a great find for my reference collection.
d) I have an Amazon wish list, so that when relatives ask me what they ought to get me for Christmas or birthdays, I can direct them to books that would be very useful for me.
Here's a list of the books on Amazon.com in case you want to skim the preview pages, read reviews, and add them to your list:
Albinus on Anatomy
Charles Bargue and Jean-Leon Gerome: Drawing Course
Drawing Lessons from the Great Masters
Lessons in Classical Drawing: Essential Techniques from Inside the Atelier