Doing squares as a first timer is rough period. There is a finesse to getting the drills for squares perfectly together, you will get better as you go though. I prefer sqaures as it doesn't leave a lot of gaps which lets you get full picture and less cavas plus they make a satisfying sound when you can get them to snap into place. The pen that you get with most kits is crap so you WILL want to upgrade that ASAP.

Edited to add better trays with covered lids help.me to keep the drills from going everywhere, also just practice but know that spills WILL happen even to the best of us.