How to Normalize a feature
Normalization is rather common. I think you might want to consider the distribution of your data and whether you want to do anything with your outliers. Some popular normalization techniques: min-max and z-score. You will see tons of resources by googling them. From the limited amount of time I work with income data, sometimes you might want to test with a log scale as well as the top 1%-ers tend to skew the normalization as well.