I believe you do the action over and over Example: Every time you mine a block your mining skill increases a little
Yes, like volga said, you level up your mcmmo stats by repetitively doing the activity that the skill is in. Examples: -mining increases your mining skill. -hitting people with swords increases your sword skill. -chopping wood increases your woodcutting skill. -falling and dodging attacks increases your acrobatics skill. -Repairing items increases your repair skill. Ect..... you get the point.
Well, there are different types of McMMO skills. Excavation, Herbalism, Axes, Swords, Unarmed, Mining, Fishing, Woodcutting, acrobatics, repair, archery, taming. Excavation levels up by digging with shovels, the higher the excavation the rarer items you can find (glowstone, music discs etc). Herbalism levels up by farming, I have the highest on the server c:. Herbalism gives you Double Drop chance, Green Thumb chance (autoplace) and many other things. Axes by hitting people with axes but the most efficient method is by enderman grinders/ spawners but you cant do this until your citizen. Axes are not nerfed on Minetime so they break armour extremely quickly if you have high axes, max is 750. Swords doesn't give much apart from a bleeding chance. Unarmed increases damage, gives you an iron grip (can't be disarmed as easily) and the disarm attribute. This helps you disarm other players and steal their weapons! Again the higher the unarmed the more likely it is to disarm. Mining goes up fairly quickly, it gives you more of a chance of double drops etc. My best place for that is /warp A-mine but you need A-Prisoner. Fishing is boring, but it gives you a chance for rare items plus you can use autofish on a hacked client but there are none out. Woodcutting by cutting wood. Acrobatics is handy it gives you less damage (rolled/Graceful landing) whilst falling and you can dodge hits decreasing the damage. Repair lets you repair things quicker and easier and at 750+ you can salvage items (if you get a chestplate a terrible enchant, right click on a gold block and you get given 8 diamonds). Archery gives you better chance of dazing someone (giving them blindness/nausea for about 5 seconds) and finally, taming. Taming is the most underrated skill since it goes up my taming wolves, this is extremely hard but will pay off greatly by being able to spawn wolves at your side with a simple click with a bone in your hand. This would be ok for pvp but the wolves would get demolished fairly easily. I hope this is a long enough post. P.S My herbalism is over 1500