Are there any simple ways to tell if somebody has a risk for stroke?

Medical history. Yes, if someone has a history of diabetes, hypertension or prior strokes/tia's, they carry an increased risk of having a future stroke. Additionally, atrial fibrillation or a history of abnormal blood clotting are risk factors for stroke.
Many risk factors.. Prior stroke/mini-stroke, heart attacks, smoking, diabetes, high blood pressure/cholesterol, atherslerosis, infections, medication uses/chemo, connective tissues disease such as lupus/rheumatoid arthritis etc...Having more of these factors increases the risk...Thus prevention and treatment of existing illness as best as possible... Good luck.