RF Online Info: Articles: Leveling Quickly
Below are some tips I've picked up on how to maximize your XP and PT gains. All of this is based on my findings during the Beta.
From level 1 to 20, you're best off soloing. The levels breeze by and it is beneficial to keep your essential PTs high. If you are a warrior, you'll probably also want to keep your ranged skill high, so that you can wear ranger armor later in the game. It also can't hurt to level a secondary damage type... for example, if you're a spiritualist, it may be a good idea to keep your melee PT at a reasonable level, just as a fallback. Remember, PTs can only go up against monsters that you are able to gain XP from. If you become too high of a level and one of your PTs is too low to attack appropriate level monsters with, you've successfully dead-ended that PT.
The bottom line is, keep a close eye on your PTs at all times - you don't want to dead-end yourself. This doesn't mean you need to be a PT zealot and keep your PTs maxxed out at all times - it's simply a warning that you can deadend yourself if you're not careful.
From about level 20 on, solo XP grinds to a near halt. Grouping is by far the best way to level at this point, even if you are just duoing. For larger groups, try and focus on "Ace" monsters. Ace monsters hit just as hard as their normal counterparts, they just have a lot more HP - about 5 times as much. While your XP per hit won't go up against Ace monsters, the XP bonus upon killing it will. By a lot. RF Online is very generous about how it divides up this XP bonus. As an example, I was in a group with a 29 spiritualist, a 27 warrior, a 20 spiritualist, and a 21 spiritualist (myself). The 20 spiritualist and I were gaining XP at a rate of one level every 10 minutes. Soloing for that same level would have probably taken us about 2 or 3 hours. Even the 29 spiritualist was getting faster XP with the 20 spiritualist and I in the group. RF Online handsomely rewards grouping.
So, whats the catch? The catch is your PTs aren't increasing very fast (or at all), especially if you are one of the lower level characters in the group. So what can you do to stay on top of your PTs? In order to gain melee, ranged, or force PT, you need to be able to take away about 2% of the monster's HP with every attack. This means increasing your damage output any way possible. For starters, make sure that you are using an appropriate level item - if you're a level 28 spiritualist, you better be using a level 28 staff. For a big damage boost, find and purchase an Intense weapon from other players. Intense weapons basically have the strength of the next higher level weapon - so if you had a level 28 intense staff, it would be just as strong as a level 30 staff, only it can be used at level 28.
Another strategy to keep your PTs high while in a group is to mix up the type of monsters you're killing. Pull some "normal" monsters from time to time - everyone should be able to raise their PTs against them. Yes, they die quick with 4 to 8 people hitting them, but RF Online's respawn rate is very high. You shouldn't have much of a problem finding a bunch of them.
If you aren't the main tank in your group, your defense PT is probably not increasing at all. It is actually extremely difficult to deadend your defense PT, but if your defense PT is low, you could be missing out on thousands of maximum HP. So how can you keep your defense PT high? For starters, try and rotate the main tank job around the group. The best way I've found to keep your defense PT high, is (after grouping) buying a TON of healing potions. As in, 4 bags full of healing potions. Pull a monster to a secluded part of the zone - somewhere where other players won't find you and wandering monsters won't attack you - and let it beat on you. Put a heavy object on your potion hotkey and go take a nap. Your character automatically uses a potion whenever they get hit and your potion hotkey automatically replenishes itself when a stack is exhausted. Is this method expensive? Most definitely, but when you think about it, you would have ended up spending a similar amount of cash on manually raising it.

