The most convenient Swedish-English / English-Swedish dictionary is probably tyda.se. Before you finish typing the word you are looking up, it shows the list of words. You don't need to specify whether you are entering a Swedish or English word. If you type an English word, the list of Swedish corresponding words appears AND YOU CAN LISTEN to the pronunciation of each Swedish word! One caveat is that you cannot look up for more than 30 words per week for free.
An alternative online dictionary is Lexin. Its Swedish-English dictionary is not as user-friendly as tyda.se, but it offers Swedish dictionaries for other languages, too, including Albanian, Arabic, Bosnian, Croatian, Finnish, Greek, Kurdish (Kurmandji and Sorani dialects), Persian, Russian, Serbian, Somalian, Spanish, and Turkish.
For words related to higher education, try the online dictionary by the Swedish Agency for Higher Education at www.hsv.se/densvenskahogskolan/svenskengelskordbok
For a printed copy of the Swedish dictionary, Norstedts appears to be the most reliable.
For a pocket-sized dictionary, see this post.