I tend to guess based on past experiences what exposure to use at what ISO and then observe what the light meter in the viewfinder is telling me once I've input the settings. If it's within a certain margin as mentioned earlier I know that scene is good to go and will stick to those settings until I move to the next scene and repeat the process.
The guessing comes naturally with practice really and understanding where your sensor will fall short
I don't know anything about taking pics properly but they look good to me, I mainly came in to offer Kudos for catching that Lush Citroen.