In jiu-jitsu, there are a lot of things that you can do differently and still make effective, using your hips, though, is not one of them.
Every technique in jiu-jitsu (and almost every grappling technique in the martial arts) involves using the hips, but there are a few just general parts of the game that are really important even when you're just working from a position, before you even attempt the initial technique, and it's something that alot of guys, especially at the beginning level, forget.
It's really important, when you're playing from guard, or even from a standing clinch, to get your hips under your opponent. Guys who let their hips get up end up in the worst situations because you lose all of you control of your oppponent. Standing, it's important to keep your hips below your opponents hips, and on the ground it's important to keep the below your opponents shoulders. This is important even from positions like spider guard, where people forget it most often. You really have to be coming up at your opponent from underneath to work those techniques, and keeping your hips below their shoulders (part of which involves keeping your legs angled so that they will not get swept up and end up with you getting rolled in a ball) is a really big part of that.
Only move those hips at the last second, and even then be careful about how you do it, because you could end up getting caught in a guard pass. Keeping the hips low is safe, and it's important not to let them slip up until you're prepared to attack.
It's also important not to let your hips get pinned to the ground, ever. One of the best ways to pass guard is to lock your opponents hips to the mat with your body weight, so it's important (espcially if your working from a low guard, open or closed, or from a butterfly guard). It's important to keep the hips active, even if you don't have a ready opening for an attack just yet, so that your opponent can't lock them down.
If you watch world class guys work from guard, they're always moving, trying to make their opponent react quickly so that they will make a mistake. That's a great way to play that game for the more advanced guys, but even the simple movements that keep your opponent for dropping their weight onto your belt (something that every experienced gi-grappling student knows is a sign that you're opponent is establishing control) are important to remember.
Shifting your weight will keep your opponent from trusting their entire weight to the belt area, which will keep you from being pinned to your back. The movement will also give you opportunity to look for sweeps and wiggle out of that mildly controlled position should your opponent trust too much weight to it.
Just a couple of thoughts for the early morning.
Good notes. We were working a few sweeps last night that involved a lot of hip movement and it was a reminder to never be stagnant when you're vulnerable.