The more items you mark off of your to-do list, the more productive you're being, right? Actually, that may not be the case. If you've packed your schedule full of things that only get part of your attention, you may be wasting effort. Instead, do a few things well.
As productivity blog 99u points out, filling your time with tasks that only get a minimum amount of your focus isn't really being productive. It's being busy. Rather than fill up your time with things that don't get your full attention, reduce the extra projects or side gigs to one or two items, then put all your effort into those. The more focus you give fewer tasks, the better they can turn out:
You can't do everything, or be everything, all the time. For accomplished creatives, that could be a difficult truth to swallow. There are projects that may never make it past the brainstorm stage. There are ideas that may never grow beyond kernels of thought. But that means that the ones that do will be kick-arse.
While some tasks are non-negotiable (you probably shouldn't put all of your focus into taking care of just one of your three children), we often fall into the trap of feeling like things are important when they're not. Meetings and conferences are probably optional. Your five side projects could probably be whittled down to one. By removing the less important tasks, you can make your more important ones even better.