Step 1 - get a full clone of the drive
Step 2 - run data recovery software against the clone
Step 3 - if data not found, do step 2 again with another program
Step 4 - if data found, save to a hard drive (not the client original or the clone)
Step 5 - verify with client that data is 100% recovered, if so, then copy back to a folder on the original, if not, go back to step 2
A few things to note.
1. Odds of recovery go down the longer the system is used after the deletion
2. The data you are going to recover is possibly only to be found in RAW format based on file type, without the original folder structure and file name
3. Any data that has been overwritten is gone, unless there is a second copy of the file that hasn't been overwritten
Good luck.