My technique is reading! I read a lot. I read the newspaper, I read books, I read random things on the internet. If I know a word but I'm not sure of the spelling, I usually look it up on google or on a dictionary, then I try to write it a couple of times without looking at the dictionary. :)

right it's a very good question! it happen to me in spanish language . when my parents speak to me sometimes i respond them in spanish i can't make phrases , just words but i can tell you that's effective . we should practice with friends on the net with your brother or sister or even alone. but you have to repeat it till you learn by heart. good luck a_a