well it depends on what level you are,and what build you want to be.
Stamina
is going to be two-handed sword with uppercut/executioner/GDB/refecltive scales/molten armaments while dropping a standard of might does a lot of damage even on players higher then you. armor is going to be your Heavy or Medium, but I would recommend do the mundus stone of the thief if your doing a stam build is going to be 4 hunting's rage and 4 night mother (all divine's) since it will proc your weapon crit to about 20% and you will be dropping killing blows left and right.

Magic
Grab a sword and board with a resto staff to back your self up with heals and stam recovery ,your going to be running with talons/whip/searing strike/reflective scales/and invasion as for armor your going to be wearing 5 warlock set and 3 piece seducer if you cant get your hands on warlock. do 5 piece seducer and 3 piece Magnus. Do the Mundus stone of the apprentice

if you can't do either of these because of money issues or if you don't understand what im talking about, just remember that spend your AP on meatbag and fire catapaults since you can help players fighting on the ground. since the majority of front-line's are Veteran players and can kill you easily, but still take damage from these two things.

also joining a PVP guild, can give you more insight into something like this and sometimes provide the gear for you since they want to see there players win.

good luck out there, see you on the battlefield

On EU/Daggerfall the Daggerfall PvP Masters seem to welcome all

As to the build I would youtube "Sypher 1vX" for inspiration and a little drooling. Other than that @sirston‌ was more or less right on the money.

Just be in Cyrodiil and ask around in /z - something will probably come up sooner or later

the best way to grind up level's is going to be a leveling guide that you can find on the forums with the search function or youtube for grinding after patch 1.5