There are many different ways to learn new vocabulary in Spanish.
1. I personally prefer using online resources such as Quizlet and applications such as Duolingo. You can enter specific vocabulary lists onto Quizlet and practice, test and play games with the new words you have learnt! Duolingo is great for all round language practice, if you do not need specific language you can practice it on a daily basis and set yourself targets.
2. Another method I used at GCSE (and still use it now) is mind mapping. I like choosing a topic and thinking of as many words related to the topic in the foreign language. Then I cover up the words and try to remember them.
3. If you like learning with images, you can create flash cards with images on the back to help you remember the words in Spanish.
4. Another option is to create lists and learn them by covering up one side and seeing if you get the answers right.
Note: It is important to learn the word both ways as you are likely to remember it better that way. It's also important to repeat the process of learning the word to ensure you remember it.