Language is a very important prerequisite for forming a functional society since snakes are not capable of a very large range of vocalizations they might evolve and form a better communication system based on pheromones, sight signals, scents or even evolve to allow complex vocalizations after which the language would further develop into a complex one based on multi sensory stimuli and complex methods of communications would be seen some time later
Before we even start guessing anything we have to remember that snakes are reptiles unable to regulate their body temperature as effectively as mammals and birds can this changes a lot because snakes need energy in the form of heat to function effectively fire might be a lot more important to them than it is to us. To us fires were just a source of heat in most conditions you can live more or less comfortably without even the need for fire but snakes would be very much dependent on fire so you can envision that at the start a civilization of snakes would be a fire based one. Beliefs and superstitions and religions centered around fire, fire gods etc. would be highly prevalent in an early snake society
How Snakes get along
There are a lot of species of snakes on this planet. An astounding variety this could lead to formation of different ethnicity or culture based on the species a snake belongs to. There could be wars between different cultures of snakes for supremacy and since these highly intelligent snakes are (well duh) intelligent they may completely annihilate their peer snake species if they fell threatened
Conflicts would be prevalent in a society of snakes. Since a lot of snakes are venomous their conflicts would get very dirty and there is a lot of chance that snakes involved in the conflict die. Also since snakes are primarily carnivores they won't have anything against killing other snakes, eating their snakes and basically all the other kinds of gross stuff you don't want to imagine. Also the presence of venom makes investigating killings a pain. A snake could sabotage a complete batch of eggs of other fellow snakes within 30 seconds and no one would ever find out what happened until its too late.
Economy would be barter just as it started with humans but with snakes there is going to be a lot of variety humans started by bartering ans slowly as they advance they will move towards a money centered economy also as an added bonus snakes may be able to use inter species trade as a form of globalization where different species could function as different countries each of which is not completely self sufficient yet also has something the other needs. Also since we have a lot of variety of snakes this opens up a very large black market for goods trade between snake species
Politics would probably be very dirty in venomous snakes and to even avoid such accidents snakes would probably have some rule against using venom on fellow snakes any snakes found to be violating this rule would be most probably punished by death. Inter species contacts between various snake species could be the best new ever or a complete fiasco depending on how it goes and how each of the snake species view others if it fells threatened snake species could have devastating inter species war. which probably ends badly for both sides of snakes
Survival of a snake would be tough due to the small size of an average snake and the fact that there are a lot of creatures which naturally eat snakes (Birds, Mongoose etc.) survival would be difficult snakes would probably use fire to get rid of birds or other creatures n there immediate surroundings and if they are sufficiently strong snakes would even try to use birds or other small animals the way we use horses for locomotion etc. or another approach snakes could try is burrowing under the ground. Also since snakes are reptiles underground would be comfortable in terms of heat. Afternoons for snakes would be boring since they would have to simply lie in shade and wait and would be mostly unable to do anything. Blankets and clothing would appear more quickly in such a society and be of vital importance to these creatures. who would use these as insulation to protect them from cold. Also due to the fact that snakes lay eggs child rearing behaviors would be very different from human society. Eggs would be carefully guarded and the most vital part of a snake society due to their delicacy and fragility. A brood of snakes would be very weak hence well protected snake's natural instinct for biting would be well controlled from a young age (In a baby snake) and some cultures could even opt for surgical fang removal in the society. The first invention of an antivenin would be a life saver and antivenom would be available mostly everywhere and it would be easy to find. Survival in a snake society might indeed be hazardous but it will become safer and easier as the snake society develops and progresses