to start the ball rolling	set an activity in motion
to get the bit between one's teeth	begin to tackle a problem or task in a determined or independent way
at the coalface	engaged in work at an active rather than a theoretical level in a particular field
to get cracking	act quickly and energetically
to get one's finger out	cease prevaricating and start to act
to be/go at it hammer and tongs	to do sth with great energy and noise
to hit the ground running	start sth and proceed at a fast pace with enthusiasm
to be hot to trot	ready and eager to engage in an activity
to keep/put one's nose to the grindstone	work hard and continuously
to have many irons in the fire	have many options or courses of action available or be involved in many activities at the same time
to lead from the front	take an active role in what you are urging and directing others to do
to put/set one's hand to the plough	embark on a task
to set the wheels in motion	do sth to begin a process or put a plan into action
to shake a leg	make a start, rouse oneself
to put one's shoulder to the wheel	set to work vigorously
to get/keep this show on the road	start (or keep going) an enterprise or organisation
to stir one's stumps	begin to move or act
to roll up one's sleeves	prepare to fight or work
to take the plunge	committ yourself to a course of action about which you are nervous
to rest on one's laurels	be so satisfied with what you have already done or achieved that you make no further effort