You should always try to learn words in context. JPod builds a pretty good one in the dialogues, and the hosts tend to mention the appropriacy anyway. Context is usually enough to avoid using words inappropriately, but obviously it gets easier with time. If you're a total beginner, one of
thesemight help as well. I always tried to go easy on the lookups from English to Japanese at the beginning too, and just focused on learning words I had seen.