Good morning, Phil;

As Macy mentioned, an accessory viewfinder is very helpful here. For best results with a spot meter, use one with a 1 degree wide sensitive area. That will allow you to look separately at the highlights and the shadows, or the light areas and the dark areas, and see the relative "brightness" of those areas. Normally your exposure setting will be around the average point between the high and the low.

Learning about and using a spot lightmeter can be a challenge in itself. You might also look at such philosophy for lighting and exposure as the Zone System by Ansell Adams. There are others, but his is probably the best known.