I've come up with the rules for the other skills, please critique honestly. I know the paragraphs aren't exactly grammatically correct at the moment, but I'll come back and edit them later. Probably.
Medical Knowledge: You have received some kind of formal training or learning and have advanced knowledge of human anatomy. For each full day of rest, you gain 1d6 hp rather than 1d3. You may also focus your efforts on caring for a friendly pure human or mutant human, and they heal 1d6 hp rather than 1d3 hp, though you still gain 1d3 hp per full day of rest when caring for a friendly. If a friendly mutant human, pure human, or mutant animal is infected with a disease, you may focus your efforts on caring for them, which will decrease the disease's duration, effects, and increase your friendly's chance of succeeding their saving throw, the effectiveness of these being at your ML's discretion depending on the details. If you contract a disease yourself, you may also receive a bonus to the above through giving instructions to a trusted friendly when taking care of you, this of course also being at your ML's discretion.
Charm: There's just something about you that people seem to like, and you know just how to craft your words to persuade someone. When convincing/hiring a retainer, you get -1 to your roll per rank in Charm. Your retainers and followers also gain an additional 5% experience per rank in charm whenever experience is gained. The price of hiring specialists is also decreased by 5% per rank in Charm. You also seem to be able to talk your way out of conflict. Those you hire also seem to stay on with you longer, and are more loyal. (ML's note: At your discretion, if the character trained in Charm communicates with a monster party you have to roll to determine their reaction for, subtract 1 from the roll for every rank the character has in Charm depending on how well they role-play what they say. When rolling morale for the Charming character's retainers, at your discretion add 1 to the roll for every rank in charm)
Navigation: You have experience and knowledge when it comes to traversing the wilderness. You have less of a chance to lose your direction when traveling across land. (ML's note: At your discretion, whenever you roll to determine if the party loses direction at the beginning of each day of travel, decrease the party's chance of getting lost by 5% per rank of Navigation, it is at your discretion whether or not this bonus applies when traveling by sea)
Scavenging: You have had enough escapades picking through the ruins of the past to know what to pick out and take. When foraging for food in an urban area, with a rank 1 in Scavenging, you are able to find enough food for an additional person in addition to your roll. With a rank 2 in Scavenging, subtract 1 from your roll to scavenge, but going no lower than 1. With a rank 3 in Scavenging, subtract 2 from your roll going no lower than 1, and you find enough food for an additional person. At your ML's discretion, you also know how to take only the working and expensive bits off of technology and machinery, giving you a bonus to repairs of items that use those parts, and trading goods (at your ML's discretion).
Technology: You have some kind of formal training, learning, or experience when dealing with with technology of all sorts. Decrease the length of time required to study technological artifacts and repair technology by 3 minutes for every rank in this skill. Increase your chances of success on technology rolls and technology repair rolls by 5% per rank in this skill. (at your ML's discretion)
Athletics: You have spent more time training your body than the average wastelander, you are able to carry 5% more weight per rank in this skill without being over-encumbered. When making an ability check to climb, apply a bonus of 1 to your roll for every rank in this skill. When swimming, you have a 5% less chance to drown per skill rank in any situation. You can also go turns additional to your skill points without having to rest. (Skill rank 1 you can go 6 turns before resting, etc.)
Foraging: Throughout you many treks through the wilderness, you have learned what plants and animals to heat and how to hunt for food more effectively. When foraging for food in a wilderness area, with a rank 1 in Foraging, you are able to find enough food for an additional person in addition to your roll. With a rank 2 in Foraging, subtract 1 from your roll to scavenge, but going no lower than 1. With a rank 3 in Foraging, subtract 2 from your roll going no lower than 1, and you find enough food for an additional person. At your ML's discretion, you also know naturally occurring substances that can be used as medicine and for other purposes.
Sailing: You've spent enough time at sea to earn your sea legs. When repairing a ship, you count as additional crew members equal to your skill rank. At your ML's discretion, when at sea you get a 5% per skill rank bonus to all checks.