It depends from situation to situation. But heres how I would do it. You analyze the cat owners path, take routes to find out where their home is, figure out how often they leave the house. How many people are in the house, if there are any alert systems or security cameras. Also if there are any more pets that might cause a fuss seeing you, such as a dog, or a bird (Those things tweet loud don't underestimate them). Get any supplies you might need, such as something easy to carry the cat with. Depending on the size of the cat, get a towel based on that size so you can wrap it around that to conceal the cat out of sight from the outside. As well as giving them space to breathe at the top, where the towel is not concealing. Bring some cat treats too, and additionally if you're willing to put in the effort, find out the cats diet beforehand, look out for what food or treats they give their cat (Or search the house as you're stealing the cat for some cat food and treats. Snag the treats and take a picture of the food). Finally, take the cat, wrap it in a towel, take it out of the house and while you're on the run feed it a treat or two. Pet it and get it to love you forever and ever