Be sure to check out the Genki I study group that just started and see if it’s right for you to jump into.
I really like this book, but since you have A Dictionary of Basic Japanese Grammar, it’s unnecessary to buy All About Particles as well. There’s certainly no harm in having, referencing, and using both. If your funds are limited, I’d recommend skipping, or considering (the slightly more expensive) “How to Tell the Difference Between Japanese Particles: Comparisions and Exercises” (by the name publisher, Kodansha, and author, Naoko Chino).