Any action you take to avoid a collision must be taken early enough to be effective and must be large enough to be readily apparent to the other vessel.
Changing course is generally better than changing speed due to the fact that this would be more immediately obvious to the other vessel. A course change great enough to be obvious would have the additional benefit at night of displaying different navigation lights. Rule #8 specifically advises against making a series of small course or speed changes that may not be easily detected by other vessels.
At all times your vessel's course may not be a straight line. Limitations imposed by a narrow and winding channels, shallow water, or ice conditions may force you to hold a course dictated by the limits of the channel. These limitations may restrict you to making only small course changes to avoid other dangers, such as running aground.
All actions taken to avoid collision should result in passing at a safe distance. Therefore, you must carefully check the effectiveness of your actions until the other vessel finally passes you and is clear.