First is call company that checks for all utilities (usually noted as a Before you dig in your phone book, or you poco site would have the info who to call to locate). As for the tree company, make sure that they are not just some bubba with a chainsaw. Make sure that they are bonded & insured, and will clean up the mess and grind the stumps. Easy way is to check with city arborist if you have one, or angie's list.