For complete beginners, particles are markers in the sentence connecting words together. Similar to “a” “to” “and” “or” ect. For example, in a simple sentence “I am Niffer” you would say “watashi wa Niffer” ‘wa’ being the particle in this sentence. You can see a list of all these particles at Nihongo Ichiban which might seem like a lot but they are fairly easy. You could try and cram particles but it is a lot easier to learn them in context by using other resources.
I have not used any other books for learning particles but there’s a huge list of them on Amazon which you can look through to find one that suits you (if you’d prefer).
Tae Kim’s Guide to Grammar – This is a great guide to grammar for beginners. He has step by step guides for all the grammar including particles, which the lessons for are broken up between other grammar lessons so you don’t overload your brain.
JLPT Bootcamp – Has a collection of videos teaching you about particles (great if you’re an audio/visual learner).
Learn Japanese Particles – For iOS. Has lessons, quizzes, games and keeps track of your progress. $2.99
Japanese 101: Particles – For iOS. Has lessons, quizzes, and even audio files of the questions. $5.99
Obenkyo – For Android. Has an experimental particles section with a few of the basics and explanations of them. FREE
Japanese Quiz – For Android. Has a particles quiz section, but nothing on learning them, only practising their usage. FREE
Personally I prefer All About Particles. It makes sense, is easy to read, you can read it over and over and can help put particles into context a lot better than other methods. But it does help to practice using particles which, unfortunately, it doesn’t do.
Then once you’ve learnt the particles but find you’re still getting stuck, you can use this cheat sheet from Tofugu! But it is best to try and recall from memory to get your brain trained so try not to use it too much.