I like to keep things simple so I will suggest a beginner mat pilates class or beginner yoga (assuming you’ve never done either). Off the top of my head I suggest Swan I, double knee to chest, single knee to chest, spine stretch forward, downward dog, arm raise and neck rolls. All of these can be found in the suggested class formats. A class is better to ensure proper flow and that your body is warmed up prior to jumping into the stretches. Definetly NO ballistic stretches allowed. Good luck!