Use time blocking.
If you aren’t using a time blocking approach to scheduling your days, you’re probably wasting a lot of time without even realizing it. By blocking out time to work on specific tasks, you can avoid distraction and stay focused, getting more work finished in less time overall. I try to schedule all of my meetings together so they don't break up my day. I also try to only do meetings 3 days a week at most, usually Tuesday through Thursday, leaving Monday to focus on organizing my week and Friday to wrap up any loose ends.

Make a list and prioritize.
The endless to-do list can be overwhelming. Organize your project management system by due date at the beginning of the week, setting deadlines for various tasks and placing the most urgent ones first. Paired with time blocking, this allows you to always keep ahead of the game by getting the work that needs to be done first out of the way.

Have a designated office.
A lot of (if not most) virtual assistants work from home. There are pros and cons to this approach, but I find the most important thing to make working from home effective is to have designated office space. You need a workspace that is organized and quiet, free from the other distractions of home like kids or chores. Even if you live in a small apartment, set aside a quiet corner for your desk with a divider to block out visual distractions. Also, make sure you have the proper equipment to get your work done, including backup computers should your primary workstation fail.

Use excellent resources.
A craftsperson is only as good as the tools they work with. The same goes for virtual assistants: there are so many free and readily available resources for organizing administrative and creative work. The virtual office is more sophisticated than ever before, and taking advantage of all the resources available will help you be a more efficient and organized worker. From project management software to communication apps, if there’s a need to be filled, you can guarantee someone has come up with a great solution that you can use!

Make self-care a priority.
In the competitive world of business, too many people wear their sleep-deprivation and long hours like badges of honor. In reality, failing to take care of yourself leads to burn out, and being less productive when you are working. Take care of yourself, body and mind: get enough sleep, exercise, eat well, and practice whatever relaxation techniques work best for you (meditation, yoga, etc.). Set aside “me time” and time to spend with family and friends. You’ll be a lot happier and healthier than those who slave away at their desks all day.

Set working hours and stick to them.
Related to the last point, you should be realistic about how many hours you can work each day, and when you schedule them. Don't work your life away; it isn’t worth it for a few extra dollars. Be clear with clients about your “office hours” and when they can expect responses from you.

Keep a journal or thought log.
Sometimes working on a task for one client can spark ideas for another project you have to tackle later. Always keep a notebook on hand to jot down ideas quickly, so you don’t lose them but also don’t distract yourself from the work at hand.