First of all, wormhole space is not for everyone. There a great many different avenues to explore in wormhole space but the constant that links them is the mind set that is required to succeed. Whether the goal is to make money or find targets to engage in PVP, wormhole space rewards careful scouting, consideration of risks and a methodical, thoughtful style of play.
You don't need to play as described, but wormhole space systems are littered with the ship wrecks of those who have tried to run PI without checking to see if their system is secure, and the abandoned POSes of industrialists who could not turn a profit due to continual losses. If your objective is PVP, most prefer to do so without a killboard deep in the red - even if those losses can be sustained due to high income sites in the upper tiers of wormhole space.
PVPFrom a PVP perspective there are a great many excellent videos of wormhole space hunting and combat that can be found online, but by their nature they cover the interesting parts of PVP engagements. They can make wormhole space PVP seem significantly busier and more consistently tense and exciting than it is.
Finding PVP targets is often a lengthy, laborious process. Multiple evenings can go by without even seeing another manned ship in space. Those ships that are found are often sat inside a POS and only leave to do a PI run or warp to a link to high security space and jump out. If you play at a non standard time zone this can be an even more significant problem.
If you enjoy the hunting and intelligence gathering style of game play, and can put up with potentially lengthy dry periods, then wormhole space in the lower class systems may be exactly what you are looking for.
Higher class wormhole systems have traditionally provided slightly more consistent PVP opportunities; a well-known subset of wormhole corporations are present and repeatedly rolling your static connection (known as 'chain collapsing' or 'rage rolling') used to be a consistent way of finding and fighting one of these groups. Whether this will continue after the well publicised issues with rolling wormholes after the Hyperion release is yet to be seen. The increased income in higher class systems tends to bestow a slightly more laissez-faire attitude towards ship losses than you find in corporations in the relatively income-starved lower class wormhole systems. It is for this reason that I tend to avoid combat with class 5 and 6 wormhole residents; their isk has a different value to yours if you live in a class 1 to 4 system and this can make it harder to predict their behaviour.
Higher class wormhole systems also provide the potential for capital ships to be used in wormhole engagements; this can provide fights that are very different to the almost exclusively sub-capital fights in class 1 to 4 systems.
PVE ContentRunning sites in wormhole systems used to provide a significantly better income than it now does as the price of one of the key salvage components (melted nanoribbons) used to be around twice the value at time of writing. This is especially true for lower class wormhole systems as a greater proportion of the income that they generate comes from the salvage. Incursions now generate the same or better income but with much less risk than sites in wormhole space, and so many pilots have moved on to running them instead.
The main reasons for running sites in lower class wormhole systems are convenience and, perhaps counter-intuitively, risk. If you are already living in a wormhole system, getting to known space to run sites or missions is inconvenient to say the least, and unless you have multiple accounts available the wormhole will have to be your primary source of income. The risk in running wormhole sites can be a draw for people; it definitely makes the site running more exciting, if only sporadically. And sometimes expensively.
IndustryThe cost of anchoring a POS in known space can add a significant amount to the bottom line for industrialists. Moving into a wormhole can avoid some of these costs, although there is the opportunity cost of moving things into and out of the wormhole system. Anchoring a POS in a wormhole also allows you access to the otherwise low or null-sec only industry types such as booster manufacture.
Although a wormhole is technically more dangerous than high security space for doing industry, in practice there is relatively little difference. Movement of items in and out of the wormhole will only be occurring very sporadically and will most likely be jumpy straight out of the wormhole system and into high security space. The only way to do damage to a pure industrialist outside of sieging their POS is to set up an interception using a warp disruption bubble at their starbase or the wormhole link out of their system. Even the most basic scouting will avoid the interception risk, and few PVP groups will wish to spend time grinding down a starbase in an undesirable (to them) system with no real chance of a fight.
Planetary InteractionPlanetary Interaction is a great way of making isk in wormhole space, especially if you use low cycle times and manage to get into a routine of running it consistently every day. Wormhole planets are technically in null-security space and have the best possible amount of resources present on them. Although the income is reasonable for the amount of effort invested, the risk is significantly higher than pure industry and the amount of interaction that PI takes is minimal and dull - this is something that players do to fund their other activities, it is not in and of an activity itself.
The increased risk comes from the need to travel to customs offices at planets in the wormhole system, sometimes multiple times per evening on each of several accounts. This gives any hunters who are online and in the system at the time multiple windows to spot what is going on and potentially spring a trap.
Mitigating this is obviously the option to avoid doing runs to customs offices if there are likely hostiles in the system, but more often than not players doing PI opt to not even check, and simply carry out their housekeeping tasks in cheap, unfit ships with throw-away characters in throw-away clones.
Gas MiningGas mining in wormholes can be a reasonably lucrative profession; characters don't need a significant number of skill points to be highly effective. Although inconsistently available, gas sites provide a consistent rate of return when present and can be run in ships that, while not resilient, are effective gas harvesters and incredibly difficult to catch - Ventures.
Gas sites, unlike ore sites, need to be scanned down using probes, so any hostiles who are new to a system have to scan down the site or the ships that are running it before they can disrupt them. Importantly the sites themselves are fairly effective defensively; cloaked ships tend to get decloaked by the large gas clouds providing even more warning for any pilots harvesting the gas.
One of the more significant downsides of gas mining in wormholes is the large volume of the raw materials produced and therefore the number of trips required to haul them out of the wormhole. For this reason pilots who regularly do gas mining in wormholes will often have a reactions array set up at their POS to manufacture finished products from the gas instead.
SummaryMost groups that inhabit wormhole systems fall into one of three broad categories; those that exist in wormholes purely for PVP, industrial groups that attempt to avoid all contact with other players, and those that "live off of the land"; fighting in wormhole space or the known space connections and making their income within wormhole space.
It's generally a good idea to work out what you intend to be doing in w-space and read up on some of the details before committing billions of isk to stake your claim outside of known space. And have a serious think about whether yourself and your corps mates have the mind set to cope with the ever present paranoia!