To those talking about expertise - he says he's a level 24. He doesn't have access to any gear with expertise and if he's using the old expertise gear from the PvP vendor on the homeworld, all it will do is knacker his bolster.
To the OP:
Different servers have different dominant factions. On the Red Eclipse (EU PvE server) the Republic tends to be the stronger side in PvP, but all servers are different.
Some basic tips for getting ahead in low level PvP:
First make sure you understand the objective of the warzone you are playing. DPS stats, lives lost, Healing provided are all meaningless if your team fails to secure the objectives you're meant to be after.
Alderaan Civil War:
You need to capture the turrets and then hold them. Take the turrets early and then ensure that you interrupt the enemies attempts to capture at all times. Unless a captured point is under assault at any particular time you do not need large numbers of people guarding it. If a point is not under assault 2 people to guard it is more than sufficient and usually just one well geared tank can hold the point until help can arrive.
Huttball:
Make sure you have the pass the huttball command on your bars somewhere and make sure you have a key bound to it. In Huttball you need to get the ball across the opponents goal line. If you are fighting in an opponent away from the ball, you're probably doing something wrong. The only two real exceptions to this are when you are trying to clear enemy team members from scoring positions on your line or if they are protecting the middle ground prior to the ball respawning (The ball respawns in the middle if a goal is scored or if the ball if passed to an empty space - or occasionally if a player is killed and no enemy player can capture the ball from that kill). In Huttball be careful of using stuns on the ball carrier that build resolve (the white bar around the outside of the player portrait). If a player has full resolve they can't be stunned (...well in theory anyway). Stuns, snares and knockbacks in Huttball can allow you to place the ball carrier on highly damaging hazards which are good way of getting turnover for the ball.
Ancient Hypergates:
There are two pylons to be captured. Points are gained by holding the pylons until they explode (the most points), capturing energy orbs from the central room and taking them to a pylon held by your team (a few points), and killing opponents (a few points). Points can only be accrued when you're holding at least one pylon. There for you should ensure that the pylons are captured and held as the first priority. You can attempt to capture both pylons for a large number of points, but be aware that it is likely you will lose more team members this way and can potentially give the opposition a lot of points.
Novare Coast:
There are 3 bunkers each controlling a gun. 2 guns are needed to break through the enemies bases shield. Each shot that gets through the shield does damage. The middle point tend to be the most heavily contested capture point. This can sometimes lead to the gun nearest the opponents base being left unguarded or under guarded. Use the chat to co-ordinate your defense.
Voidstar:
You need to race through various areas to get to the computer core. Each area has something stopping the attackers progress. In order you have, doors, bridge, doors, forcefield, doors, computer console. The most important section tends to be the first one. If the defenders can repel the attackers and prevent them from getting through the first set of doors then the rest of the match tends to be a lot easier. In each phase there tends to be a left side and a right side to defend. Make sure no side is left undefended and be sure to communicate to let your teammates know what's going on especially if you are on a side with less people. On the bridge section you can use knockbacks to send people to their death. As with huttball be careful when using stuns and knockbacks that can build resolve.
Arenas (Tatooine, Orbital Station, Corellia - soon Makeb)
The objective is the same in each of these arenas. Kill the opposition team as quickly as possible. The main secret here is to have the team focus on a single person at a time and get them down as quickly as possible. At the same time you should try and work out who the opposition is focusing on and protect them as best you can.
General tips:
Many warzones benefit from good communication. Especially in the event of capture and hold objectives (Novare Coast, Alderaan, Voidstar). When you have people approaching you position (especially if you're the only person guarding a point) announce the enemy in chat. Additionally announce how many enemy are incoming, this allows people to plan whether to break away from their combat or to stay and fight.
One tip that may not be widely known is that copy and paste shortcuts work in general chat. If at the start of a warzone you type (but do not send)
[Name of defended point] Inc
Then press shift and the left arrow key to select the text.
Then press CTRL+X you can cut the text to the clipboard.
Then when enemies approach, paste the text with CTRL+V and type the number of enemies approaching and you have a quick system for keeping your team up to date.
The other thing you need is practise. Sometime you will get landed with a bad team (especially if you're going in solo). Don't get angry, and don't start shouting accusations at other people. Some people play well, some play less well it's just a fact of life. But one thing that's fairly universal is that if you annoy someone in general chat they are less likely to be able to play well enough to win, an angry team is a poor team.
It may also be worth trying to find a good PvP guild if you want to improve. Having a regular team that learns each others play style can make a huge difference to your chances to win.
Hopefully some of this will have been of use to you.