You are likely to learn most of your target language by reading texts written in that language. The most direct way to do so is to use a dictionary. The big problem of reading with a dictionary is that the number of unknown words will soon exhaust you if you look every one up. There are several strategies to deal with that problem:

Look up every single word for the first page, then try to understand the rest by context only. This works fine for technical articles, where all of the important words of the article are usually used in the first page of the text and then come again and again.

Look up only the most important words. This is a actually a mix of the context-only reading and the dictionary-reading. You are bound to do that if you read for any length of time. Unless you are very advanced, you will not be able to figure out each new word by its context only, and you will not have enough energy to look up every single word either. There are just too many, and if you do that you would read only a couple paragraphs a day instead of reading several pages.

Use an electronic dictionary. If you don't mind reading texts online, this is a great tool and reduces very much the burden of looking each word up. Consequently, you will be able to look up many more words than if you use a paper dictionary. In addition, you will also be able to make flash cards using your computer with very little effort. Electronic dictionaries come in various shapes. Some are handheld, some are just websites where you need to type the word to look it up. The best ones become integrated with your operating system so that all you need to do to look up a word is right click on it.