Depends on what you want done.
Changing the shape will change how your whole face looks. For example, going from a convex nose to a straight nose to a concave nose, like 3 different people.
Reducing nostril flare can only improve you appearance. People with flared nostrils tend to look like Orcs.
Narrowing the nose is pretty much hit or miss. Bridge and tip width should match, sometimes it isn't possible to narrow a tip as much as the bridge, and bridgework is usually done first. If you want to preserve your current look get a surgeon that will do what you want without changing the side profile, or persisting in something that will have a disasterful outcome.