Techniques for learning and retaining characters For many of us, memorizing characters is a difficult thing. In Chinese, just because you can speak the word doesn't mean you can read it. Just because you can read it doesn't mean you can write it. At least for me, I find myself constantly forgetting characters I used to know, especially when it comes to writing. 

Do you guys have any tips or trick to avoid this? Aside from just constant writing? 

EDIT: I'm getting a lot of answers on learning based on the radicals, which is valid and works for quite a lot of characters. But it doesn't always work. There are many cases where there are no such obvious correlations, especially in simplified characters, where many things are removed and sometimes loses the meaning the traditional character. Also, the below characters have obvious hints of pronunciation or meaning.


限制
矛盾
度
You can use a SRS (Spaced Repetition System) software, I personally use Anki to create a deck of study cards and I review them on my mobile phone. 

I also recommend Memrise.

2014 update:

I still use Anki, but combined with Google Images Search and Forvo: When I make new flashcards, I'll add the writing (hanzi &amp; pinyin), its pronunciation (from Forvo) and a picture of the character's meaning (from Google Images), that way all the card's content is in Chinese, and I avoid relying on translation. By the way, Anki now allows to synchronize media files (audio/images) between devices.

I've started using this new method few months ago, and it has worked very well for me (especially with nouns). Credits of this method goes to the "Fluent Forever" book.