How to Get My Suit Altered?

Hey everyone, I recently bought a suit that doesn’t fit quite right. It’s a bit loose in some areas, especially around the shoulders and waist. I really like the style and fabric, so I don’t want to return it. Does anyone know how to get a suit altered? Should I go to a tailor, or are there other options? Also, what kind of adjustments are usually possible without ruining the suit's look? Any advice would be appreciated!