Do one thing at a time. Do it well. Move on to the next.
There are many proponents of “multitasking” which I find is better described as the skill of focusing on one thing at a time with the ability to seamlessly shift that focus to other things as needed without losing a beat. By expanding and enhancing this skill you will find you are handling multiple tasks at the “same time” whenever the need arises.
A key concept to take into consideration here is documentation. Make notes of your progress and steps taken so you can easily return to the task at hand and know where you were; or, when in a team environment, allow another to pick up where you left off.
Working to improve recall and other similar memory functions will also help to make these shifts in focus much more seamless as well and remember to always use what works best for the environment you find yourself in.