Ensure that the piano will fit in the planned space. Measure the space and compare it with the piano's measurements, including depth along with width. You do not want to pay to have it moved and have no place to put it.
Call several piano movers and compare pricing, but don't make your decision based only on price.
Ask each company how their insurance process works if your piano is accidentally damaged during the move. Find out who ensures them and how you would file a claim.
Check the Delivery availability to deliver the piano. If you need to move the piano in two days, and they are booked up until the next decade, you may need to consider someone else.
Settle on a company and set a delivery date. Make sure you are home at the scheduled time and clear the area around the piano's new location so the movers have room to work.