When i originally started playing it was a lot of research trying to figure out which MMO i wanted to play.because since the dawn of D&D, the market has become somewhat diverse. After some heavy duty research i decided that i wanted to stick to Pathfinder. And i'll give you the reason why in the form of some superfluous backstory that you don't necessary need or want.
D&D, the original pen and paper rpg debuted in 1974 by Gary Guygax and his friend Dave Arneson. Together they continued to improve upon the original idea of the game until 1997 when TSR, the company run by the two original creators was purchased by Wizards of the Coast. WOTC continued to produce for D&D and came out with their very first D&D product which was now Dungeons and Dragons 3rd edition. 3rd edition did some thing radical in the sense that it unified both the basic D&D and the AD&D (Advanced D&D) rules into one game and did a lot of refinement to the systems to improve gameplay as well as releasing the entire backbone of the game on what is called an OGL (Open Game License). This meant that third parties could take the system that was set in place by 3 and 3.5 edition of D&D and create their own works out of it without any hassle.
One company that decided to create content for the D&D Game system was Paizo Publishing. They had created their own universe for the game as well as a large supplement of modules and apocrypha for this new world that they created. When paizo's products got wildly popular, Wizards of the Coast pursued them for copyright infringement which angered paizo as they were doing nothing wrong acording to the OGL. Paizo decided to break away from the D&D scene, taking with them all of the content that had made them famous, rewrite all of the rules for D&D 3.5 and release their own pen and paper which they titled Pathfinder. Pathfinder, as such has taken the world by storm and has become one of the most popular pen and papers to date and with good reason.
I digress though. Since i've started playing Pathfinder i've been playing both roles, the role of DM (Dungeon Master) who creates the story, atmosphere and direction for the players and the role of the player, the one who creates the dialog and interacts directly with the world that the DM sets up. The player side is pretty easy, the hardest part is mustering the courage to actually have a conversation in character with your fellow players who are all doing the same. But as a DM it gets very difficult you have to keep track of the players stats, the monsters, the monsters stats, the initiative rolls, the dungeon itself, creating unique and engaging prompts for each room and making it all challenging and have that fun factor that keeps hem coming back for more. For people who are less on the creative side, there are the paizo official modules which offer you a linear quest line that has suggestions on monsters and prompts premade for an engaging experience that if you follow them will make for a successful session. But for people like me? i hate that. i can't sit down and study a dozen rooms, then recite them verbatim on game day. I prefer fluid experiences for my players and to do that i've discovered that i just need to make out maps, with named locations and maybe a prompt here or there and just fly everything else off the cuff. to me it becomes a much more organic experience for me which translates to a much more organic experience for the players. Best yet, i'm currently making my own campaign which is a series of modules strung together in a linear story.
It's important to get a feel for how you can DM Successfully. or play successfully for that matter. What is fluid for you to have a great user experience is crucial in a pen and paper because it really is all left to the imagination and without that you'll find your experience lacking and thus unenjoyable in the end.