There are no two ways about it. If you want your viewers to really understand what it's like to be at a festival. To feel the atmosphere. To hear the sounds, imagine the surroundings and smell the sweat you've gotta be up close.
No good standing 100 metres away with a telephoto lens for a sanitised view of it all. If you can't smell the sweat of the dancers you're not close enough!
Getting in close to festivals requires a wee bit of gumption. Not for the faint hearted, you need to act like you belong there - even if you don't feel like you do! If you're in the wrong place somebody will tell you to get out of the way (usually a big beefy security guard!) but until they do be bold and get in the action.
A useful trick is to take photographs with both eyes open. It takes a bit of getting used to but when you're in a crowded situation shooting with a wide-angle lens it's all too easy to bump into people, brick walls and other things that can knock you out! When you have both eyes open you're actually looking through the viewfinder but keeping an eye on the world around you at the same time. You can also see things that are about to enter your viewfinder so you can quickly press the shutter to get a shot.
I'd tell you that I always do that but I'd be lying. I'd like to do that but am actually pretty much blind in my right eye so it wouldn't be much good!
For a different view at festivals I know quite a few photographers who carry step ladders around with them. Just small two or three step jobs that let them get up above the crowds to shoot down on the festival for a different view. I've seen them standing in the middle of the street as the parade just goes around them and they get some wonderful bird's eye view shots. Of course a technique like this won't work for a parade with big floats but it works well for those with mostly people just walking.
Probably the biggest tip I can give you in terms of photographing festivals is just to let your hair down and enjoy it as much as everybody around you. If you're running round with a serious look on your face worrying about the next shot people aren't going to take too kindly to you photographing them. But if you've got a big cheesy grin on your face, are greeting everybody in a friendly manner and just having a whale of a time people will line up to get in front of the camera.