Mercenary concepts work great in tabletop but in LARP they can get very lonely. Most LARPs are communally driven with the expectation that players help each other out. Yes, merchants will sell you potions and gear, and you will have to pay for enchantments, but most players expect fighters to fight and healers to heal; all for free. When town fights happen the entertainment package is set up for everyone to be inclusive and join in. If you start by constantly asking about money before you lift a finger to help you will get a bad reputation. If you start nickel and diming every adventure, then other players will start to hammer you with fees. So, it can be quite challenging.
A better way to use this concept is to have a mercenary background. Come to your first event and see how the culture of your game works. Some games may not event have the treasure policy or the in-game coin among your player base to "afford" you. You need to look at the plot and game style and in smaller chapters you may become a spokesperson to get a better deal with your nobles or employer when offered mods. You may want to join a militia or the local town guard and negotiate your "pay". Be flexible and see how this develops. You are at the begging of your career as an adventurer. In larger chapters you may even be given the opportunity to join an existing mercenary faction among the players. There is a lot of adventure in the alliance system, you just need to be flexible and adaptive enough to grasp it and achieve your goals.
Hey there! I'd like to throw out a mercenary playstyle we've seen work very well at our games.
Being a mercenary towards PCs isn't so great. You show up in town, you're a new face, and then immediately start demanding coin for your services and people in most circumstances are just going to grab another fighter and go on without you. But! There will always be mods/missions/bounties, etc which offer a promise of reward, which as a mercenary is right up your alley! Look around at game for these sorts of adventures. They're absolutely available and if a reward is already being promised, no one's going to bat an eye when you, as the respectable merc that you are, go ahead and ask for it!
Now when it comes to the big fights at the end of most game days, you'll probably want to just participate without worrying about who's going to pay you. There should be a loot drop at the end anyways, so you'll still get your pay! In general it's a good idea to play nice with the other PCs. If you do something to tarnish your own reputation, it could come back to bite later on. So don't be that broody/murderous/selfish/obnoxious/etc prick that no one wants to hang out with because people won't hang out with you and the weekend won't be as fun. Still, you can find many ways to play a mercenary which don't cause problems with the player base and are enjoyable for you to play as a PC!
Obviously things run differently chapter to chapter, so things may be different where you are vs another location. For us in Vegas, there's been several mercenary PCs who have all been able to find proper mercenary work from a plot perspective and it's gone very well!
To piggyback off what Richard and Heinricht said here:
If you have a character with a mercenary background, depending on how you roll them and where you're rolling, you can discuss that with your prospective plot team. If they don't previously have as many opportunities with rewards up front due to the story of their game, talking to them in advance can help you understand if that's a viable background in the specific lands they're in, or open up opportunities that may encourage more straightforward mercenary work.
With coming in with early XP levels, there's still a lot of potential with that to say in your background that the reason you ended up with the skills and gear you have at the time of game start for you is that you are a mercenary.
Your character may have moved to the area where the game is occurring because you have heard of it being more risky but also more lucrative (Out of Game translation: the Average Player Level is higher, the level totals are higher, therefore the treasure policy is higher) than taking direct contracts. As a sellsword coming into the area, that change in culture if there is one can be interesting to roleplay out. Instead of getting a mere silver to creatively take on minor monster problems for traveling merchants and minor nobles as something of a soldier of fortune, you hear you could be fighting collaboratively to take down the Evil Power Master and catching gold or better from his minions.
LARP is cooperative, and a smart mercenary would understand the cost and benefit of working with others. Instead of having to keep silver and gold aside to pay directly for healers, the healers in your group will often do it because it makes sense. You're up there hitting things and keeping the threats from getting to the back line where they are, as long as the distribution of resources afterward is equitable, casters and martial classes stay happy.
Taking it as a craftsman skill (for 2.0) or profession (for games playtesting 2.1) will confer benefits worth 1 silver piece per logistics period for each rank at check in. (For Profession, it's either a silver piece or a Crafting Material, which is relevant to production skills.) This is at the rate of 2xp per time you have taken the skill, and adds flavor to your character.
Your play style as a mercenary will be highly dependent on how you want to play as a PC and your own out of game physical capabilities. If you can't hit the broad side of a barn while throwing things, maybe being a sword jock is more your deal. Sword and board is pretty popular. If you're the type to run around all over the place or like to be sneaky beaky and get behind the enemy, scout archetypes might be more your speed.
It brooks mentioning that you will be able to rewrite your character after your first event if what you have made isn't your style. However: If you aren't sure about your character, you have until the next event you play as your player character. This could be a month, or it could be the very next day if you go to two mod days in the same weekend. Even if you change the way your character is built, you cannot regain a chance at new starting gear tags, though.
You can also try out different builds in freeplay before going to your first event to see what your mercenary would be capable of here: https://freeplay.alliancelarp.com/
I'm personally a big proponent of trying to NPC first in your desired chapter. Some camps have free NPCing, others have the NPCs pay a reduced rate to help cover food and camp costs, but you'll be provided costuming and weapons and can talk to your plot team about styles you want to test out. It's a great way to understand the culture of the chapter and can be a big idea generator. I went as an NPC for my whole first year. The experience in understanding fighting styles, the world, and how the rules work from a practical standpoint was a gigantic help.
AGB Plot/Tech Goblin/Baby Rules Marshal
I have played a mercenary type, here are my best tips.
1.) Most towns split loot through, this is extremely lucrative so any mercenary should be happy to hook into that funding and eager to ensure they are involved.
2.) Mercenary contracts are great side RP and coin. Want a contract to make sure your friend has extra protection? Sure I can do that for a few coins. Make these optional extras, leverage personal connections, Knights want their squires to be safe. Nobles want to splash coin to show how important they are and to protect visiting dignitaries.
3.)Never withhold reasonable aid to the town, this will give you a bad reputation and make it harder to offer services.
4.) Expect that potentially at some type you'll move from Mercenary to authority, if you take that path, you need to be ready/willing to slow down on the merc work as you move into your new role.
At the end of the day a mercenary is someone who fights with the intention of getting paid. That's what MOST of the players at the games I play do. You can be the nicest, sweetest, healer-est guild master in the campaign, but if your coin primarily comes from killing goblins and taking their belongings.... you're a merc.
Adventuring, especially if you are good at combat and are willing to take risks, is VERY lucrative. Agreeing to go on mods in exchange for a cut of the loot that drops will make your character more money than you EVER would demanding paid contracts in-game.
I encourage you to go to whatever game you will play, learn to fight, and make friends. You'll get paid VERY well.
If you absolutely want to play up the mercenary bit, then you can shift your focus entirely to the treasure. At the end of the fight when people are celebrating or sharing inspirational speeches... you could be counting the treasure for distribution to make sure everyone gets paid (including yourself).