You'll hear EVE described as rock paper scissors, and to some extent it is true. For every ship there is a counter, the reason that good pilots become great is they understand the strengths and weakness of their own ship, and that of their opponents.
Choosing the fights where you stand a chance of winning, and running from any fights where you have no chance. There is no shame in running from a fight you can't possibly win. So how do you build up a knowledge of EVE combat fits? Part of it is experience, the more often you fight, the more you learn, the better you get. But it's not just about flying your own ship that you need to understand, you need to know what other people can do, you can't possibly have skills for every ship in the game, so you need a way of comparing them. There are a couple of free tools that allow you to do exactly that, to build fits for ships and to compare them, with your own skills, and that of a higher or maxed player.
EFT or EVE Fitting Tool, built and maintained by the pilot Gripen, this has been the mainstay of most pilots for as long as I have been flying. It's very easy to use, with a clear interface, can store your API details so that you can see how the ship will work with your pilots skillset.
Evefit started life as Python fitting advisor, it's an open souce project very similar to EFT (in fact I believe it came about due to Gripen going inactive for a while, and the need for an updated version of EFT). EVEfit does now appear to have a larger development team, and publishes updates faster.
Both allow implants, and fleet bonus's to be calculated. Both allow importing and exporting from the EVE client. If someone links you a fit in game which looks good, save it in your personal collection, then you can later export it to your chosen fitting tool. To a large extent it doesn't matter which one you use, as long as you are comfortable with it, and know how to use it.
There are also several very active community forums in EVE, these are not directly related to any one alliance or play style.
Has a large dedicated fittings section and repository, any person can upload their fits, and allows other people to comment on, give advice on improvements, and has a rating system for fits. Fits are displayed clearly on their own page, with a graphical interface, and an internal search engine allows accurate search based on ships, and tags. It allows exporting into EFT/Evefit, by searching the existing fittings database and reading the comments you can start building up your own collection of "good fits" to experiment with. As with any community it attracts trolls, so don't take anything personally. As a rule of thumb searching previous fits prior to posting is a good idea, you'll often find that a similar fit has already been posted. Overall Battleclinic is still quite noob friendly.
Often refered to as the bastard stepchild of Scrapheap-Challenge, a community of bitter vets, and trolls. Failheap is however an source of excellent information, and tactics, and quality knowledge. Many of the regulars have been playing EVE since it's origins. It isn't always the most friendly of places, and stupid or noob questions can result in mild to serious flaming.
That being said, I still advocate joining and having a poke about in their ship setup hanger, and piloting in practice forums. The fittings section is based around a normal forum rather than battleclinic's own graphical display pages, fit's are usually posted in a format readily copied into EFT/Evefit, but finding individual fits can involve trawling lots of posts.
Run and moderated by CCP this is the interal EVE forum, in order to post you must have an active EVE account, posting is by character name, so many pilots prefer posting with an Alt char, rather than their main. A good source of technical information and it's worth following the test server forums for planned changes to ships and modules.
Not a forum, but a collection of blogs all related to EVE online, quality of information and advice varies from blog to blog, but the amount of knowledge freely given is astounding. Find a few blogs that deal with your playstyle and follow them.
An amazing source of intelligence, as eventually everyone dies, and those losses are often recorded on one of the main out of game killboard. All modules are displayed for all to see, that secret winning fit, now published. By looking over the kills and losses of experienced pilots you can see how they fit their ships, and what they died to. Copy some of their fits into EFT/Evefit, see how they stack up against each other.
The two main killboards are:
The more you read, the more you start to learn.
Knowledge truly is power.