I took a picture of my mock setup to give a better idea of what I'm working with.
Basically, I'm will be using relays connected to my Raspberry Pi that I intend to use to control a series of lights (21 to be exact) via a web server. I already have the web controls working but I just need to scale up my current model. I haven't had any issues with my setup but one of my relay's response time seems to have slowed down after some use. I was wondering if I am causing some damage to them with my current set up, or if there's anything I can use to protect both my board and my relays. I've seen people talking about using transistors and resistors but they don't mention how to arrange them and my technical background in hardware isn't quite there yet so I can't figure it out on my own.