Pure-blood Lore
If you are considering making a pure-blood character it is important to understand their unique background as we head into the rise of Lord Voldemort and the First Wizarding War.
Being Pure-blood 
In canon pure-blood status is defined as a person who can claim to have 100% magical blood throughout their family lineage with no muggle blood mixed in. It's also widely understood, though seldom discussed, that being 100% pure-blood is all but impossible at this point in history. Most families would have a secret half-blood or two hidden somewhere in the family tree they just refuse to admit to. Being pure-blood is less about the science and more about the history. A list of 28 pure-blood families exists in canon though families who were friendly towards muggles, such as the Potters, were excluded. On Foe
.Glass we do not limit players to the canon pure-blood families. Players are welcome to create their own pure-blood families.
Pure-blood Politics
Pure-blood supremacy (Bloodism) has always been part of the magical world. Many wizards think their magical abilities and lineage make them superior beings compared to muggles and by extension those with muggle blood. Magical society has long had strife with muggles. Many magical folk feel angry that they are forced to live in secrecy when it is muggles who are inferior to them. Many wizards throughout history have taken to the idea of a new world order in which wizards rule the world and subjugate muggles. This ideology is exactly what will both shape pure-blood culture and give rise to Lord Voldemort during the Foe
.Glass timeline. While not all pure-bloods become Death Eaters per canon we know a significant portion of pure-bloods supported the ideals of Voldemort to some extent. Of course not all pure-bloods believe that they are superior to muggles. Pure-bloods who support equality are often called blood-traitors and looked down on by other pure-bloods, even their own family though.
Influence & Wealth
It stands to reason that when a family has existed in society for many generations they have time to cultivate influence and power if they want. The same would apply to economics, the longer you have to invest in an economy the greater your assets become, if you're savvy and playing with a good hand. While not all pure-blood families are influential and wealthy we see in canon that a great deal of the people who are influential and wealthy are pure-blood. Influence and wealth in the wizarding world works much like it does in ours. You're either born with a silver spoon and keep it through responsible management and investments or you do something amazing that pays off in spades. Since the wizarding world is modeled after Victorian England we would look to the aristocracy and elites of that era to mirror the kind of wealth and influence our old pure-blood families of means would have. For many of that status work is a way to pass time rather than financially needed. Political roles and jobs are likely used to increase or cement influence in society. Money would likely be put into investments, particularly property and business enterprises. Social circles are small and consist of other elite people. As the wizarding community is relatively small and very insular gaining access to 'the room where it happens' is more likely to happen when everyone knows your family and have for generations. There are of course pure-blood families that are not well to do and are still valuable members of the wider magical community.
Pure-blood Society
On Foe
.Glass we will see pure-blood society loosely based on aristocratic life in Victorian England based on strong suggestions from canon. Many pure-blood wizards would see their lifestyle, preferences, and practices as the de-facto magical culture. With no muggles in the family to bring additional cultural influences pure-blood wizards would have the strongest ties to wizarding culture overall. Pure-blood society is traditional in it's social behaviors and norms. Members of this social circle would likely be conservative compared to many half-blood and muggleborn peers. Their social practices such as young ladies making a debut into society and marriages being socially engineered by family members seem old fashioned even in the 1970s. Exclusive fancy balls and events are the backdrop to their summers and holiday seasons. Even within this elite society there are levels. Pure-blood families with long lineage and a long history of wealth and status would sit on a rung higher than pure-blood families with 'new money' gained in the most recent generations or those with controversial opinions.