Do you have a plumbing diagram of what is supposed to be done? This allows you to follow or verify the job.
Also, try to avoid using 90 deg elbows and go with sch 40 sweep elbows if they have them.
Determine how and when they plan to test the plumbing at end of job with air or with water or both?
Mark the pipes where they end at the equipment pad such as skimmer suction, main drain suction, pool return, etc.