At my high school at football games, front row in our stadiums is ASB and they ALWAYS play a huge part. We have certain cheers that are easy that they always chant to with us (ex: if you like it, say go big red, GO. BIG.RED. And of course ASB chants out the last part with us). When a couple people get involved everyone gets involved.
Also to keep the crowd include we have something called a get up cheer. Everyone in the stands sits in their seats while all the cheerleaders huddle together. Then, someone starts yelling out the class grades (freshman, sophomore, junior, senior) and you stand up accordingly, then at the end we chant our team mascot at the end and everyone stands up at once and chants! There is a video on YouTube but I'm on my phone and can't link it right now, but I will when I get on a desktop. To teach everyone the cheer it's probably best to do it at a pep assembly.
Try to get ASB to help out, cause they do A LOT for my school