I'm going to keep this short and simple, as there is a lot of misconceptions about how these two values are calculated. I gathered this data through testing and playing over 250 scenarios and accumulating around 11,000 RvR kills on a Runepriest! For the classes I list, assume the true is the same for the Destruction equivs. I am a Runepriest, so I will post some of my general farming tips and strategies for that class.
I've joined a match with only 7 minutes left to go, only to have 1,500 more Renown then anyone else in the entire match. I've joined matches late and earned the most RP/XP out of everyone in the scenario. Farming XP/RP is pretty straight forward, there is no complex math involved or crazy weird mechanics for calculating it. After reading this, you should be able to go out there and maximize your farmtr0n.
Experience Breakdown:
Experience (XP) is gained through kills and kills only. You do not gain XP for doing objectives, healing people, or damaging them. You gain much more XP for getting the killing blow, and even more XP if you get a solo kill.
To get a 'kill', you either need to be near the person when someone in your Team kills them, OR, you kill them, OR, you need to 'tag' them for death, aka, do any amount of damage to them atleast once. When they die, even if it's 10 minutes later, you will be credited for the kill. If you're a Runepriest, it's important to lay some of your crappy dots, or AoE dot, on enemies, just to 'tag' them for kills. By doing this as an RP, you can easily tie the lead for kills on your team, despite not really doing anything to anyone.
XP is ratio'd to your level. The higher level you are, the more XP you'll get out of the final XP pool for your team (more on this later). So if you find yourself 'doing' better then other players in your scenario but getting less XP, it's probably because they were 1) higher level then you, or 2) in a better team then you which earned more pool XP.
You also gain a Win XP bonus at the end. Currently a Tier 3 Win gives me 8,500 XP. I do not know the rates for the other Tiers.
Renown Breakdown:
Renown (RP) is gained by getting kills, killing people, and solo-killing people. You also gain it through healing people other then yourself. The general forumula for Renown from heals is the amount you healed the player for divided by 100 (rounded down). So if you heal someone for 370, you will get a +3 RP update. So if you are a Runepriest, having HoT's all over the place is pretty important for farming Renown. If someone falls into the lava, thank whoever knocked them there, and then spend all your AP healing them with Grungi's Gift untill they die. You'll get quite the RP for it, I promise
Much like XP, Renown is pooled for your team and split between you at the end of the match. It is not scaled to your level, so if you are low level, you can still farm high amounts of RP and beat out high levels on the final score chart.
You also gain a Win RP bonus at the end. Currently a Tier 3 Win gives me 600 RP. I do not know the rates for the other Tiers.
Team Breakdown (IMPORTANT):
Experience (XP) and Renown (RP) is shared with your team. If you play in your own team, you keep all the xp/rp you earn. If you suck at earning xp/rp, you'll want to join a team with xp/rp farmers (Runepriests & Brightwizards). If you are a Runepriest or Brightwizard, you probably will want to be in your very own team. Runepriests can't kill anyone, so you'll get crap XP, but you'll get the most Renown out of any class. My RP can farm 4,000 RP in a scenario, but I'll usually get less then 2,000 XP! My friends Brightwizard can farm 20,000 XP in a scenario, and also farm 4,000 RP as well. BW's are the scenario farming champs if they go solo, however, this is only true if they have a dedicated Runepriest in another team healing them.
Remember, everything you earn is shared with your team, and everything they earn is shared with you. If you are on a team and you are the best player in terms of earnings, this will work to your disadvantage. If you are a Brightwizard or Runepriests, try to get on to teams with other BW's and RP's. If you're on a team with nothing but tanks and melee, and they're higher level then you, they'll get 80% of everything you earn, leaving you with nothing much to brag about.
There are 5 teams available to join during a match. You can change teams at any time during the match by click on the White Flag button on your screen. You're usually put on Team 1 or 2, sometimes 3 if it's a full match (most players I've seen is 18 per side, aka 3 teams of 6 players per side). If you want to try solo, leave your Team and join an empty one like Team 4 or Team 5.
And that about wraps up the guide. To farm high XP/RP, you generally need to run strats different then strats needed to win the match, so you will need to find a nice balance between maximum farm-mode and win-mode, as winning in itself gives huge XP/RP bonuses. So don't exactly throw a match just to farm a bit of XP or RP, as it'll not be close to the bonuses you get from winning. However, if you already are going to lose, might as well stop playing to win and start playing to farm.