This topic has been addressed before-just search the forum.
"Foundation & Earth Structures" by Budhu covers many of the fundamentals. "Foundation Engineering" by Jumikis, 1987 also does excellent coverage.
While book learning will get you about half way there, I'd consider finding an experienced shoring designer and pick his/her brain to get you the rest of the way.
FHWA has several publications dealing with soil nailing, anchored walls and MSE walls. Cantilevered nongravity walls (sheet pile or soldier pile) should be covered by any reasonably good textbook.