Picking a secondary profession

I just started guild wars with a few friends. They are expierenced with this game, but i'm not. I've played WoW for a few years if says anything.

Anyways I've tried Paragon, Ranger, and all the casters and find them boring as a main class. I'm wanting to make a Assassin, but I have no idea what's a good secondary.

My main thing once I hit 20 is to do tons of PVP.

I was thinking A/MO for the extra support, but I also thought A/R might be good since maybe add poison for my daggers might make me own?

I don't know, any advice would help. I don't want to play an easy character to level to 20 just to understand the game. I just want to pick a main character for now to main.

1) If you want to PvP seriously, make a PvP character. It is possible to PvP with PvE characters but you'll need to spend a lot of cash buying skills, equipment, etc.
2) When you get to a certain point in the game, you'll be able to change your secondary profession as much as you want. What you choose becomes irrelevant at this point.
3) Look through PvXWiki to see what kind of builds are used.
4) Poison alone doesn't make you own, nor is it worthwhile to spend resources as an Assassin in Monk stuff to keep you alive.

Most common secondaries are A/W, A/E and A/D, for varying builds.

If you want to play assassin like an assassin, with daggers, go A/W for the increased attack speed stances (flurry, tiger's stance) to get your combos off faster. You also get access to distracting blow (for interrupts) and balanced stance, which certainly help in parts of the game.

As for PvP, listen to Marty Silverblade and make a PvP character once you're comfortable playing assassin in PvE and have unlocked enough elite skills to give you some options.

You choose a primary class and a secondary class, not two classes; your secondary should enhance competencies your primary already has, not give you new ones.
I.e. a warrior is a good choice because you can use and IAS (increased attack speed) to attack faster and therefor deal more damage, monk is a good choice because you can bring a hard rezz (a rezz that can be used more than once), but a monk would be a bad choice if you bring heals for yourself and allies because that's not what a sin should do.
As Marty already said you can change your secondary freely later on, so you should choose a profession that is useful on low levels; I adivce warrior, because you get Flurry, Distracting Blow, Wild Blow and a few other skills, and they are effective even with zero attribute points spend.

Ok I guess i'm going to make a Assassin/Warrior.

Now my question right now is, should I then make a PVP only character right now or should I level a PVE chracter (Assassin/Warrior) to unlock skills and stuff?

I don't really understand how the whole unlocking system works were I unlock stuff in PVE and then I can use it on PVP only.

You can either unlock skills through playing the PvE or you can unlock skills via Balthazar Faction which is earned by playing PvP. A skill that is unlocked is available to any PvP character on your account, but PvE characters have to either get it as a quest reward, purchase it from a skill trainer or use a tome to learn it.

You can farm the Zaishen Elite area for Balthazar Faction until you have enough skills to make a decent build, then move on to other types. http://wiki.guildwars.com/wiki/Zaishen_Elite_(mission)
Note: There is a daily cap on the Zaishen Elite for Faction. http://wiki.guildwars.com/wiki/Balthazar_Faction

One thing I would suggest to do if you have the time is play a bit of PvE for each Campaign. This allows you a quick unlocking of some basic skills - like if you play through Prophecies starting zone you can pick up all the basic starter skills for Warrior (as well as other classes). Also doing the starter section for Factions allows you to unlock some basic skills for warrior, assassin as well as other classes. Same with Nightfall.

If your more interested in PvP rather than PvE missions, quest's, etc.. then I'd suggest spend 30-60 min blitzing through the PvE starter quests for each campaign you have for a starter selection of skills.. then creating a PvP character and hitting the Balthazar quest's and elite's for faction each day for points to unlock more skills..

note - For the "starter" quests in Factions and Nightfall, you only have to mission/quest up to the point where you've talked to all the trainers when deciding a secondary profession. Once you have done this, you'll not get anymore skills from quest's. Prophecies is basically the same - once your up to the part of choosing secondaries, you can go to each trainer.. do their quest and get the skills.. then move on to next traier.. once done all skills quest's.. you can stop.

Also, if you play through Nightfall's PvE missions/quest's you will get "Hero Points", you can use these to unlock some more skills as well. So if you do do some PvE'ing in Nightfall, use the points to unlock warrior & Assassin skills for your PvP'ing.. Would only take an hour or so to gain enough hero skill points to unlock 3-5 skills of your choice this way.

http://wiki.guildwars.com/wiki/Hero_skill_point
http://wiki.guildwars.com/wiki/List_...skill_trainers (this shows what skills you get from where)