Frarc,
What type of character do you want to play.... even before template considerations; good guy, bad guy... hero or murderous villian, etc.
Then you can narrow the down the play style and faction that might appeal to you..... If you are drawn to the good side then TB or CoM might appeal to you, if you want to explore your dark side then SL or Minax.
What shard to you play? I find the best way to get involved in factions is to connect with a few guilds in game that can show you the ropes. They will help you build a suit, make template suggestions based not on just good pvp templates but what templates work in the group tactics and templates used in your faction which might also include a template they are lacking.
A good faction guild will teach you more then pvp which is only a part of the overall faction system (some will tell you pvp is the only part that matters and others will say pvp is only a minor part). They will teach you the in's and out's of faction play. How sigils work, statloss, town control, traps, points, silver, rank, guards, defending, raiding, etc, etc.
If you are looking for a shard to start playing factions, I suggest Great Lakes or Origin. GL has 4 active factions, and its one of the few shards that you can still get the full faction experience. Origin might have increased faction activity as people will want to test the new faction changes before they go live on the production shards.
Lore