Swedish Dictionaries by the Foot
Swedish words’ shapeshifting tendencies can be jarring to English speakers. While you get up to speed, print dictionaries will be mostly ornamental.
Let me explain the "by the foot" bit, as a quick demonstration of why you won't use a print dictionary much. You know that "foot" is singular and "feet" is plural in English. In Swedish, fott is the singular and fötter is the plural (both "indefinite"). However, even my copy of "Prisma's Swedish-English and English-Swedish Unabridged Dictionary (Third Edition!)" has no entry for fötter. I'm pretty sure the Fourth Edition's going to be the same.
Certain Swedish verbs also have forms which dictionaries don't list. The assumption is that you know how to figure this sort of thing out even if you don't know the word -- just as you intuitively do it with English. That intuition with Swedish comes easier than you may think. But until you have it, you could rifle through pages never finding the word you need.
Technology is on your side though, as free resources are at hand which are much more accommodating than print. The three sites below should have you covered.
1) Ord.se -- NE Nationalencyklopedin AB runs this site. They vastly overhauled the site earlier this year, improving the experience both on smartphones and computers. Ord.se now handles phrases like komma undan ("to escape"), or bli ifrån sig ("to be beside oneself"). The updated site also allows you to type in a conjugated verb and get a result, instead of requiring the infinitive or the present form of the verb. It's also gotten better about accepting the plural forms of a nouns, though it's still not perfect at this.
NE's paid version (called "engelska pro") is about US$3 a month, renewing automatically. I called my credit card company to let them know a foreign transaction was coming, and everything has worked out perfectly. Unlike my #2 and #3 sites, NE places no ads on the page.
2) Bab.la is my other go-to site, and I have it open almost always. It's better than Ord.se at predicting words and phrases as you type, and it almost always finds the right word no matter which form you enter. You can enter a conjugated verb form, the plural form of a noun or adjective, and generally get the right info. Another strong feature is that you can start with Swedish or English words.
Bab.la provides real-world examples for words it knows, often drawn from official proceedings and news reports. It also does this to some extent when it can't find what you're looking for, so always scroll down to check. You'll often find examples which are more useful than dictionary definitions.
A final bonus, Bab.la has a verb conjugator. It covers many common Swedish verbs. For this you must know the infinitive form, which you can find easily back on Bab.la's dictionary page.
3) Tyda was recommended by one of my teachers. She likes that it has many newly added Swedish words which other sites miss. I haven't needed to use it that much, but I'm not operating at her level, either. Keep it in your bag of tricks.
When all else fails, you can try a translator site. Type "Swedish translation" into Bing* and you'll get a handful of options, including Bing's translator. I really treat this as a last resort and consider it a bit of a cheat. Beyond this you have raw Internet searches. I have tracked down a few words or phrases in this way -- usually technical terms, very new words, or slang terms.
* Disclaimer: I work for Microsoft.