My suggestion is read and read and read some more.
 Keep the dictionary nearby but don't look up every word because it's too tiring to do that and all words don't have equal importance.
 After reading, say, 10 pieces from different genres, and the same words keep popping up, and you haven't figured their meaning from context,
 then look those up.
I never bought the idea of "thinking in another language".
 I mean, my native lang is English and I don't think I think in English...not until I express myself to someone does a language come into play.
I think instead that the more frequently you see certain constructions repeated in a 2nd language,
 the less time you deal with processing their meaning.
英語で考えろ、と指導する人がいるのは知っているけれども、そんなことはできないんじゃないかなー。上級者はできるらしいけど。
僕の感覚で言うと英語力と読む量は正比例する。