Recently, we’ve been playing with Unity’s Shuriken Particle System for Shield For Hire. Both for the intro orb effects and collisions/skill effects. There are plenty of tutorials out there that can help you get started, including a very detailed one at 3dgep.com. It was written in 2012 so it’s a bit dated, but it does a nice job of breaking down what each module within the Particle System component does (which is where the magic is). Youtube has been an essential learning tool for specific effects (ex. fire).
I also found it very useful to download free effects from the Unity Asset Store and tear them apart. I learned a lot about the particle system just by studying how each module was used by other developers. KY has some great free effects to learn from. If you have trouble scaling down your effects without losing quality, there are a couple of developers that include an effect modifier in their bundles (not free though).
We had a blast playing with the modules, and even saved some crazy effects that we might use in the future. Remember to play with all the modules to see what you can come up with. Have fun with Unity’s awesome Particle System!