You may also want to consider buying an extra seat so you are guaranteed to commandeer all 3 seats in an outer row. It's worth comparing the cost of the extra seat to alternatives, especially if you are paying for MCE or are considering premium economy.

You can also try to sit in the last 2-3 rows on widebodies as they typically have 2 seats in the outer row due to the curvature of the fuselage. However those come with other downsides (no extra legroom, very loud as they are close to the bathrooms or galley (or both)