Do people still use radicals to look for a word in the dictionary? I think most people use Hanyu pinyin nowadays.. the lazy man's method
But as a general rule, look for what's on the left of a character, or what's on top. For example, for words like 家 or 草，the radical to search for is the one on top. For words like 难 or 伟 , the radical is on the left. Sometimes it's by trial and error..if you can't find it by one radical, try another.
