Muscle memory is by far the best way - in that sense, learning ASL is somewhat like learning to play the piano. At first you have to continuously follow the notes, but after a while, the first page of Fur Elise becomes second nature. So, as always with languages, practice makes perfect - you just have to trade in your pen for your fingers in the case of ASL.
For fingerspelling, you can practice in all manner of ways, including choosing a word at random from any book/dictionary, or fingerspelling whole sentences in whatever book or magazine you have open.
For recognition, apart from the obvious choices (course videos, online dictionaries, Switched at Birth episodes, etc), you can also watch ASL interpreters on the news. Whatever you choose to watch, try to focus on the various aspects of ASL - the sign itself, facial expressions, style, etc.
While there aren't many ways to easily write sign languages down, there are also flashcards of various types that you can use as aids - e.g. Barron's 500 Flash Cards of American Sign Language - but just going through the cards without making the accompanying gestures won't help you much.
Finally, while flashcards for recognition must have images (or videos, if we lived in the world of Harry Potter) on them, keep in mind that for recall, you don't need must beyond a list of words. You can probably get away with a stack of cards with the word on one side and a verbal reminder of some sort on the other. If you really don't remember what the sign looks like, you can then check in an online dictionary, but for the most part, this should be sufficient for review purposes.