I have often found that the sound of background music can be soothing, and will fill in those awkward silent pieces between poses. The music shouldn't be too loud to the point where you cant hear yourself think, but at a volume to where if you talk the client can hear what you are saying.  I have recently started sending questionnaires to select clients to gather some information on them. Where they are from, what they do for work, hobbies, favorite genre of music... This usually works best for my seniors, and couples. I then take the information that they give me and it will give me the info I use to create a comfortable environment for them. With this tool you should have enough to ask all the right questions. This will then make your clients feel like they can speak to you. This just breaks that barrier of them being strangers. I take my small bluetooth speaker with me to every session. Todays hits radio on pandora is usually my  go to, mainly because everyone knows what is going to play. These tips are what I use to create that good relationship between my clients and myself. It much easier to start and end a session on the good foot. I strongly encourage you to get to know them before you meet in person. Just so that initial "hello" isn't forced. Become the friendly photog that everyone loves to be around. The less tension, the better the images is what I go by.