I've abandoned many decks almost completely because I made too complex cards.

Make the cards simple and combat interference. That doesn't mean you can't learn complex concepts. Now that I've got it right, I can go through hundreds of reviews per day if I've fallen behind a bit, and don't find it exhausting. If I manage to review every day, it's because I'm doing it first in the morning.

I use a plugin/option to make the answer show automatically after 6 seconds, so it's easy to spot cards that are formatted badly or cause interference, and take too much time.

Some general Anki tips: If you use it to learn a foreign language use the Awesome TTS plugin. Whenever Anki displays a foreign word it should also play the corresponding sound. Don't try to consciously get the sound. Just let Anki play the sound in the background.

I use a plugin that adds extra buttons to new cards I changed it in a way that gives the 6th button a timeframe of 30-60 days till the new card shows up the second time. I use that button for cards that are highly redundant.

Frozen fields is a plugin that's useful for creating cards and I wouldn't want to miss it. It allow you to present specific fields in the new card dialog from being cleared when you create a new card.

Quick Colour Changing is another useful addon. It allows you to use color more effectively to highlite aspects of cards.

I have written my more general thought about how to use Anki lately in another thread: http://lesswrong.com/r/discussion/lw/isu/advice_for_a_smart_8yearold_bored_with_school/9vlh

On of the core ideas that I developed over the last time is that you really want to make cards as easy as possible. I think the problem with most premade card that you find online is that they just aren't easy enough. They take too much for granted.

Take an issue such as the effect of epinephrine on the heart. It raises hard rate. Most of the deck that you find out there would ask something like: "What's the effect of epinephrine on the heart?" That's wrong. That's not basic enough. It's much simpler to ask: "epinephrine ?(lowers/raises)? heart rate"

I think that idea also helps a lot with language learning. I think the classic idea of asking "What does goood mean in French?" is problematic. If you like in the dictionary you will find multiple answer and the card can only hold one answer. A card that just asks: "good means ?(bon/mal)?" is much simplier. I have made a French Anki deck using that principle and it's astonishing for myself how well the learning flows.

If someone wants to test the deck I'm happy to share it. I would estimate the effects to be that for a lifetime investment of 20 hours you get the 200 most common French words + ~100 additional words. For most of the verbs you will be able to recognize the three basic times (present, future and passé simple). I think you will know the words well enough to understand them when you read a test. If you want conversational fluency with those words I think you will need additional practice. Deck is (French/English) For those of you who want to start using Anki I think it would be a good start.

If I would for example start now a Vim deck I would group functions. Take something knowledge like:

w next word (by punctuation); W next word (by spaces) b back word (by punctuation); B back word (by spaces) e end word (by punctuation); E end word (by spaces)

This make cards:
?(w/W)? -> next word by punctuation
?(w/W)? -> next word by spaces ?(w/b/e)? -> next word by punctuation ?(W/B/E)? -> next word by spaces

I would also add: ?(q/w/e/r/t)? next word by punctuation ?(w/s/x)? next word by punctuation

This gives you probably a rate of being able to answer the card in ~4 seconds. Cards that aren't hard. You can simply integrate a new deck of 500 of those cards in an hour once the deck is ready.

Using it regularly is the most important thing by far. I don't use it anymore, the costs to starting back up seem too high (in that I try and fail to re-activate that habit), I wish I hadn't let that happen. Don't be me; make Anki a hardcore habit.

When using pre-made decks the only efficient way is to follow along, i.e. if you don't know the source book/course it's not very good. Partial exception, vocabulary lists.