What I do when reading in another language that I'm comfortable with is keep a notebook handy. If I come across a word I'm not familiar with I write it down quickly and then carry on reading. When the reading session is over I look all of the words up in one sitting, and write down their meanings. This exercise is usually enough to fix the meaning in my mind and I don't need to look at the notebook again. Whenever possible I use a dictionary written in the language concerned.
While learning a language I would use a bilingual dictionary, but once the language is more or less mastered I find it much more effective to not rely on a translation.
Student or Learner