The most common standard adopted for responsive design is a 12-column layout, but that doesn’t necessarily mean it’s the best. In reality, you could chose to use any number of columns and still make an effective responsive design. A large part of how many columns you choose will be down to personal preference and the size/type of content you’re setting up.
I personally stick with a 12-column design as it’s the most common type to see in the wild. As such, if I’m looking for tutorials on how to set something specific up with CSS, they’re most commonly written for a standard 12-column layout. It also helps that my Bootstrap setup is a 12-column layout, too, so that makes the crossover quite easy.
I know this is kind of a non-answer, but I hope it’s at least marginally helpful. You may want to check out 1stwebdesigner.com’s helpful guide to fluid grid layout to get some additional brainstorming ideas.