I have been playing MMORPGs for almost 7 years now and I must say that SWTOR PvP is the most fun I have had in a very long time. The warsones in SWTOR do not have brackets, so everyone from level 10 to level 50 are in the same games. The game will scale your character's health and damage up if you are lower levels so that you have somewhat of a fighting chance in PvP. I do not recommend going into warzones and expecting to actually do anything until you are at least level 14, when you get your out of combat sprint. Having a static out of combat sprint will allow you to catch up to other players and actually contribute to your team. The only things that matter in lower level PvP is the amount of abilities that you have and the talents that you choose. Having knockbacks, stuns and cc is always helpful in PvP.
Learn the gametypes. There are three different warzone gametypes so far in Star Wars: The Old Republic. All of these games are fairly easy to understand and you should not have any problems with strategy unless you are playing huttball. It is always nice to have premade teams but it is almost necessary to have good communication in huttball if you want to win. There are tons videos all over the internet that will help you out with passing positions and overall huttball strategy.
Valor points are important. In PvP, you will gain valor points that will raise your valor rank. Having a high valor rank will give you access to mounts, titles and the best pvp gear available at level 50. The best way to earn valor points in warzones is to obtain medals. Each medal will give you bonus valor and warzone commendations to spend on pvp gear. There are tons of medals out there for things like 2.5k single damage hit, 2.5k single heal, 75k total damage, solo kill, killing blow, etc. Figure out which medals you can obtain based on your class and try to get as many as possible each game.
Find a good PvP guild. If you plan on playing SWTOR for the PvP, find a guild that runs premades. I have found a guild that runes premade warzones all day and we rarely lose. This is one of the best ways to quickly and easily win games and earn valor points. Find a group of people in your guild that you get along with and try to PvP with the same people so you can get a feel for their basic strategy. Be sure to use skype, vent, teamspeak, etc to communicate with your teammates because most pugs have no coordination and you can easily get the upper had just by talking to each other. Having the ability to voice chat is much easier than trying to stop and type out something to your team.
Keep Playing. As you PvP in SWTOR you will learn what works and what doesn't. Read up on PvP with your specific class and see if there is anything that you are missing or talents that you should choose. Getting feedback from other players is one of the best ways to catch things that you might be missing about your class or spec.