I agree with most of the comments. Time blocking in the calendar is most efficient. And to be strict on that - notifications off, look for a quiet area in the office where you can not be found ;-), and turn on your noise cancelling head phones - then GOOOO!
maintaining focus during project development is crucial for success. I find that setting specific time blocks for focused work and eliminating distractions such as emails and social media helps me stay on track.
Get a person who can keep you accountable! I mean time blocking, schedules and plans everything is great! But accountability to finish tasks on time is the best way to finish the tasks on time!
I have an accountability partner with whom I do weekly check-ins! We set goals for each week and make a list of tasks we need to finish to complete those goals.
Throughout the week we keep each other accountable and make sure we're not staying behind!
Pick one task and focus on it intensely, rather than juggling. Start with the task that requires the greatest concentration and give it your undivided attention.