Finding good screen printing is very valuable for people who are constantly making customize shirts. It is a pretty affordable way to get a certain point across, or if a person is planning for any type of event or team.
Searching locally in the area is the best way to go. There can be screen printing Sacramento options, or really any major city in the United States. It does not make any sense to go with a company that is halfway across the country, because the shipping costs are going to be a lot of money.
Ask them for a sample or past work if they have any. Most of them are going to be more than willing to show off what they have done in the past. This allows a person to understand exactly what they should expect from the company in the end.