Improving skills through EP is not always realistic, to be honest. A gaming session might only cover a few hours of campaign time. Allowing a character to improve one or two different skills from Fair to Good in that time is far-fetched.
But it’s fun for the players, and psychologically satisfying, and so recommended.
As an alternative, or in addition to the methods described above, the GM may allow traits to be raised through appropriate amounts of training time. This would require finding a teacher (which would cost money) or taking an appropriate job (which may not be totally dedicated the skill you wish to learn, and so take longer). It’s also possible to learn something on your own, but the GM should double the time required.
If using the Objective Character Development system, the GM may (or may not) require that EPs be spent in this manner that is, you can’t spend EPs unless you also take the time to train.
The GM sets training time and costs, and difficulty of finding a teacher. The teacher has two skills that must be considered: Teaching skill, and the appropriate skill being taught. The player may need to roll the dice to see how diligently the character studied the skill. The die roll should be on an attribute such as Willpower, Drive, Zeal, Wisdom, Self Discipline, Self Motivation, Psyche, Intelligence, etc. If the player can give a valid reason why the character is extremely motivated to learn this skill, the GM may grant up to +2 to the trait tested.
The GM may request a single die roll, or a roll per week, month, etc. If multiple rolls are called for, at least half of them should succeed to earn the skill improvement.
Example: Billy Blaster, space cadet, is back at the Academy after his first tour of duty. He considers his Fair Laser Pistol skill to be substandard. He takes a six-week training course in Laser pistol use, taught by an instructor of Superb Laser skill and Great Teaching skill. (Since Billy has Gift: Employed by Space Patrol, this is free training for him.)
The GM decides that Billy’s player needs to make a Willpower roll for each two-week period to see how dedicated he is to studying. If at least two of the three rolls are Mediocre or better, Billy can raise his Laser pistol skill from Fair to Good, given the length of training and quality of the instructor. Had the training been shorter, or the instructor worse, he would have needed a preponderance of Fair or even Good rolls to have successfully raised his Laser pistol skill.
Remember that it is much easier to improve a skill from Poor to Mediocre than from Great to Superb. Require more time, or higher Difficulty Levels on the Will rolls to raise an already high skill.