There are different ways for cutting, holding. If you don’t have a big project that you only have a few cuts to make it’s not worth it to get an electric compound miter saw.
A good quality manual miter box will do. You can purchase these from your local homebuilding center such as Home Depot or Rona or even home hardware carries this type of tool. Don’t buy the cheapest one they have because they are also very inaccurate. Ask the sales clerk which Mitre box is the most popular one sold. It should come with a good quality saw to prevent which chipping as your songs through.
If you’re doing more than a simple job with a few mitered cuts it’s advisable that you buy a compound miter saw this will greatly reduce getting tired from sawing and also increase accuracy over a period of usage because you won’t get tired.