If you are completely new to Python (or programming), I’d recommend to start with the Codecademy Python 2 tutorial. It’s free - you just have to register to the site -, and interactive. They also have a paid tutorial for Python 3, but the differences are only marginal and in Grasshopper you’ll use IronPython 2.7 eighter way!
Once, you’ve got the basics of the language down and want to explore stuff with Python in Rhino, you should work through the Rhino Python Primer, which is also free for Rhino users. The most important thing, when trying to learn something is to get experience through projects!
After that you can embark on the particle stuff! A word of caution though, Grasshopper is not ideal for this, since it comes with a lot of baggage and is not really meant for animated interactivity, but it’s feasible.
There are lots of great tutorials on YouTube (cf. Jake Hebbert, Daniel Shiffmann, Sebastian Lague, etc). Not all of them work in Python or even Rhino, but they oftentimes explain the theoretical part very well.
You should also absolutely check out Craig Reynold’s paper that started the craze back in the late 80s.
And here are some examples of mine done in GHPython:
This thread also contains some interesting topics about particles and other creative coding endeavours:
And last but not least something fun to watch:
I did this simulation about a year ago in C++ (openFrameworks). It shows autonomous agents fighting over food for survival. A little macabre, but if you look closely dead once become food (or poison).
