This page summarizes some of the techniques I use for solving this puzzle. It is not a step-by-step walkthough of a solution. It may help to first be familiar with the techniques I use for the 5x5x5 cube.
The following notation is awkward but precise:
Place the puzzle flat on a table and call the top face A. There will be a ring of 5 faces that touch this top one. Call the one facing you B and then proceed around clockwise to C, D, E, and F. All of these faces are on the top half of the puzzle. Now consider the bottom half of the puzzle. G will be the face opposite of F (left side facing slightly away from you), H will be opposite of E, I will be opposite D, etc until you end up with the bottom face L.
Turning a face clockwise 72 degrees is represented by the face's upper case letter (e.g. F). The inner slices are represented by lower case letters (f). A letter followed by a tick mark means to turn the face counter clockwise by 72 degrees. A letter followed by a number indicates that the move should be repeated multiple times (e.g. F2 would mean to turn face F twice).
Pieces are described by the faces they are closest to. An upper case letter means the piece is actually on the face, while a lower case letter indicates that it is one space in from the face. When a piece is in the middle, no letter is used for that particular dimension. So, ABF is the top-right-front corner.
Like with all cube puzzles, the spin of the corners always is equal to 0 mod 3, and flipping of middle edges must be done in pairs (total flips is equal to 0 mod 2).
Unlike the cube puzzles, the primitive move (turning a face or slice) is always an even permutation of each category of pieces. For example, turning a face will perform a 5-cycle on corners, which is an even permutation (even permutations are those that can be constructed from an even number of 2-element swaps). With the cube puzzles, the basic move is a 4-cycle (odd permutation), which means you can get into situations where you need to swap one pair of edges and one pair of corners. On a 5x5x5 cube you can have additional parity problems where it appears you need to swap a single pair of side edges. On the dodecahdron, none of these problem arise since the permutations of various types of pieces always must be even.
With 12 faces, the dodecahedron is a lot bigger (230 pieces not counting centers, compared to 20 for a 3x3x3 and 92 for a 5x5x5 cube). This means that you have a lot more rearranging to do in order to solve it, but you also have a lot more "scratch space" to work with. Overall I find that this makes the solution conceptually simpler but it takes longer to execute.
Faces A, B, F, and I work together similar to how U, F, R, and D work on a cube. Many of my basic cube operators translated to the dodecahedron using this mapping, perhaps because I focus on the URF corner and its surrounding pieces on a cube.
By the way, from now on when I refer to an edge such as BF, I am really referring to the triple of BFa, BF, and BFi (the middle edge and its two side edges).
First, solve the bottom edges (LG, LH, LI, LJ, LK). This should be easy to do intuitively. You can alter anything else in the puzzle aside from the edges you have already places.
Second, word around the bottom layer placing pairs involving the bottom corner and its adjacent edge that doesn't lie in L. For example, place corner LHI along with edge HI. The top layer and all five upper faces can be trashed. Generally I assemble the pair in the upper face adjacent to the pair's final location, then move it into place. For example, when working on LHI/HI I would probably arrange the pair in face B then do something like IB'I' to move it down into place. At this point the bottom face and most of the lower faces (G-K) should be solved. All edges/corners in the upper faces and top face are still scrambled.
The third phase is to solve the 5 corners that touch 2 lower and 1 upper face (for example BHI) along with the two adjacent edges that have not yet been solved (BH, BI). Placing the first edge is easy since the related upper face (B) does not have to be preserved. Adding the remaining two pieces without disturbing the first edge is very similar to how pairs were placed in the second step. The top face is a good scratch space, as are the upper faces that you haven't worked on yet. But be careful not to destroy your work as you go. For example, once you place BHI/BH/BHI you should take care to preserve B. At this point 10 corners 20 edges have been solved.
Step four is to solve the remaining edges and corners that aren't in the top layer. Once again build a pair (such as BFI,BF) and then drop it into place. Use the top layer as scratch, but preserve everything else. After the completion of this phase everything except the 5 corners and 5 edges in the top layer will be solved. You're almost done.
There are actually four different things that now need to be addressed. Each can be done indepdenently (assuming you know the right operators). But moves are very constrained since almost all of the puzzle has been solved. Here is the order that I approach is, not because it makes the solution any simpler, but merely because it makes more visible impact right away and prevents me from getting lost during longer sequences.
edge-flip: FC' B2I'H'B2 CF'
Since we want to preserve the rest of the cube we need to undo the side effects. We can do this by reversing the edge-flip, but in before we do that we'll twist A, thus flipping AB and AF:
double-edge-flip: (FC' B2I'H'B2 CF') A (FC' B'2HIB'2 CF') A'
It looks complicated but it isn't if you realize that the second moves in parentheses are just the inverse of the first group. The FC'/CF' pattern moves top layer corners out of the way. The rest (B2I'H'B2) just turns the AB edge around and moves it back.
single-corner-twist: F'IF I' F'IF, twists ABF clockwise.
We can then combine that operator with its inverse to twist one corner clockwise and another counter-clockwise without any side effects. I won't bother spelling out the entire sequence. Once you are finished with these first to steps the top face should all be one color but the rim around it will stil be scrambled. You might want to twist A a few times to find the position with the least amount out of place.
edge-2-cycle: (FC' B CF') A (FC' B' CF') A'. This will cycle AB, AF, CH. You can turn A multiple times in the middle as long as you reverse it with the corresponding number of reverse turns at the end. This will let you create cycles with other edges in A other than AF.
corner-3-cycle:F'I'F A F'IF A'. This will cycle ABF, AEF, BFI. As with the edge cycle, you can substitute multiple turns of A if you wish.
Finally, in theory you could eliminate the first three phases and solve the entire 3x dodecahedron with the primitive flip/twist/cycle operations above. Personally I find it a lot easier to take advantage of the additional degrees of freedom in the earlier stages rather than conceive of everything as a series of 3-cycles.