1. Set yourself very short-term goals. Goals that can be achieved in mere hours. Break everything up. That's not to say you can't work for solid days on one thing every now and again, but if you're like me it'll probably be the exception.
2. Actually goals are not what you should be aiming for. Becoming an autodidact is about building habits. Habits that ensure that you learn. Goals have to be set and will stress you out, habits ultimately become second-nature.
3. Don't force yourself to do something that you're losing interest in. Very few people would be able to manage that without ruining another part of their life.
4. If you're losing interest you should often just move onto the next thing. The trick however is to make sure that everything that you move to is difficult, worthwhile and requires you to learn something. You have to make sure that even though you're the same short-attention span kid that you used to be you're always learning something new. You can always go back at a later date when you're less bored by a topic.
5. Always do what you love. (Okay, this isn't strictly necessary, it's more of a sanity thing. You can't work as hard when you're not enjoying yourself. You will burn out.)
6. Write down everything you learn in as concise and clear a way as possible -- especially the things which have really blown your mind -- also, if it's code have examples you can look at. Every couple of days pick up one of your black books and skim it. It will jog your memory and is kind of fun, but remember that the point isn't to remember everything off by heart: the point is to know frames of reference and be able to pick things up again if you need them. You're not studying for a test.
7. Don't overdo it. If you're close to an emotional breakdown you need to stop and think about why you started. Find balance.
Don't get too hung up about remembering what you've learnt. Just push on with the next thing and really just move forward as fast as you can. What I find is that I very rarely remember the content of what I learnt before, but I do remember where to find an easily accessible resource that refreshes my memory quickly.
The rationale behind this approach is that a) the brain (at least mine) is fantastic at indexing information - but not so great at putting it in its long term memory bank. And b) that it probably works this way because it doesn't want to store in long term memory stuff that it doesn't have to. So it takes a note of what it's seen, gives you a little index to let you find it again if you need it - but discards the rest. It'll store in long term memory the stuff that you come back to over and over again...
It's also important to bear in mind that particularly when you are starting out in a learning endeavor you really have no idea what of the basics you're really going to have to have memorized in a rote fashion. So don't fret it. Learn it, take a note of it, move on.
edit - part of what I hate about schooling in general is that they force you to rote learn heaps of stuff you probably won't ever use. And the brain hates it. No wonder kids in general hate school.
I pick a goal i want to accomplish using the discipline i want to learn, and start messing around while looking at tutorials that take you step by step through the thing you're doing in front of you, occasionally using a manual or google to lookup things i dont understand.
