Step1
Decide what size dictionary you need. If you're a beginner and not sure how far you'll go with your Spanish language learning, start with a small dictionary with around 2,000 words. An intermediate level dictionary, with around 30,000 words, is good if you need to build your Spanish vocabulary. For more advanced studies, look for a Spanish-English dictionary with 60,000 words or more.
Step2
Consider which variety of Spanish interests you most. Do you want to focus on the Spanish of Spain or of the Americas? The choice isn't absolutely critical because the differences are no more dramatic than the differences between U.S. and British English. Still, if you have a strong preference, get a dictionary based on your favorite variety of Spanish.
Step3
Short-list some Spanish-English dictionaries. In your local bookstore or online, identify 3 to 5 bilingual Spanish dictionaries that meet your basic requirements. Once you have a few in mind, you can check them for overall quality.
Step4
Make sure the dictionary offers multiple translations where appropriate. For example, if you look up the English word "close," there should be an entry for the meaning "to shut" and another for "near." A quality Spanish-English dictionary should tell you the Spanish word "copa" means not only cup, but treetop and the suit of cards known as hearts, too.
Step5
Look for example phrases. A good Spanish-English dictionary shows you how to use Spanish words. Under the word "gustar" (to like), you should find at least a simple example like "Ella tiene gusto de películas románticas" (She likes romantic movies). This is even more important with common multipurpose words. The verb "echar," for example, can be defined as "throw," "give" or "add." What's more, it's often used in idioms like "echar en saco roto" (to do something futilely).
Step6
Check that any unusual usage of a word is explained. Learning Spanish will be easier if your bilingual dictionary lets you know when a Spanish word is slang, vulgar or archaic. Yes, "huevos" means eggs, but it has another meaning a Spanish learner should at least be aware of.
Step7
Try out the pronunciation notes. Spanish spelling is phonetic, but when you're learning, pronunciation isn't always obvious. Vowel combinations like "eu," "uo" and "iu" can be confusing and the letter "r" has different pronunciations depending on the letter it comes after. A Spanish-English dictionary with easy-to-understand pronunciation notes can keep you from learning words incorrectly.