Step 1: Don't pay for D&D
By no means should you actually buy 5E (or 6E) books or any other edition's books. There are dozens of free D&Dalikes online which were created by people who gave a shit. After extensive playtesting I found out that 5E, while playtested, wasn't really given a shit about. Essentially it's like drinking Pepsi. Everyone's second choice.
So I'm going to make the choice for you: the best starter D&D game is Basic Fantasy. It's simple enough anyone can play, and has enough game there that people will actually feel the RPG gears in motion regardless of GM skill. Also you can print out necessary sections and it won't be a big drain on your printer ink or paper stock. It's at cost to print, so buy half a dozen copies and give them out to your players.
"But everyone I hear about wants to play D&D5 or Pathfinder!" You don't want those players anyway, believe me. Either put up a flier offering to teach a game you can be a master of with an afternoon's read through, or pull people from your circle of friends to start a group. Link them to the free PDF on Drivethru if you want. There's no investment other than dice.
Buy two sets of dice. One for you, the other for players. The player dice can be cheap. Your dice should be Gamescience precision dice (preferably some form of tinted clear dice). They are worth it to insure fairness. Sell the cheap dice to the players if they want them for cost. Use the money to buy another set of cheap dice for players.
Once the game actually starts, use the first four-hour session to generate characters. With the other three hours and 45 minutes, begin to generate the world with the players. Specifically involve the players in this process. Figure out the big questions: Where is the game beginning. What is the region's environment like? What's the dominant religion? What's the status of the government? Don't burden your group with stupid questions like why is the party adventuring or why is the party together - nobody asks these questions of themselves in real life. Just know that they are, and discover why through play.
Also don't ask any stupid questions about what you're trying to accomplish with the game, what tone it should take, what the plot is, etc. Someone once asked me what the tone is for my campaign. My answer is "life". Life is full of drama, angst, stupidity, ridicule, ineptitude, genius, love, laughter, fear, insanity, despair, rationale, curiosity, anger, and that wonderful feeling you get when you take a HUGE shit. Having a tone other than "life" means you should be writing a screenplay, book, or something else that doesn't involve other people until later, when they will fix your mistakes through collaboration. RPGs are unlike other media because they are collaboration in real-time.
At the end of this session you can run a brief scenario - a shopkeeper, his wife, and son (make up names, GM) are on their way from Somewhere Else (make up city name) to Home Base (make up name of area PCs are going to call home base at least for a few sessions). They are waylaid by hostile humanoids in the area (bandits, barbarians, a mobile army unit of an invasion force, a mercenary group, a local police force extorting hard working people, goblins, beastmen, neanderthals, orcs, half-orcs, quarter-orcs, lizardmen, etc). They want money and possibly depending on the group the kid as well. Stress to the players this doesn't have to be a combat encounter, but say nothing more. Then make up a non-hopelessly evil reason the interlopers want the things they want, and give that reason to the players if they ask for it. Then seriously consider any solutions the players present. Here are the baked-in solutions for the scenario, they are not all-encompassing:
1: Boring: The PCs attack the hostile humanoids, killing them until the noids retreat (or potentially to the last). This is the boring standard solution to the puzzle. I recommend 1/2 XP for this solution (because presumably the players are beginners - experienced players would get 0 XP). Be sure to let them know they are not receiving full XP for this solution, and to try to do better next time. This is important because you don't want the players to become standard D&D5E and Pathfinder players (who inherently suck). The in-game outcome of this is the shopkeeper is very happy with the players and gives them a discounted rate from here on out (just subtract a coin from any prices of his wares, keeping in mind he still needs some money). His wife bakes them an apple pie as well. Be sure to add meaningful and in-game rewards to things or you'll end up like standard D&D5E and Pathfinder GMs (who inherently suck).
2: Semi-Interesting, evil: The PCs turn on the shopkeeper, and give into the noids demands, perhaps even attempting to forge a new relationship with the formerly-hostile group. Give them full XP for this, but when they look for the kid in the back of the wagon, he's missing. Depending on whether the noids wanted the kid or not, the PCs may still be in for a fight. Even if their isn't a fight, the kid escapes to tell the authorities. The PCs are now considered members of the noids by the human settlements, and may still not be considered members of the noids by the noids themselves. Give them full XP for this, but don't tell them they'd get 1/2 XP for the other solution as the players may learn the wrong lessons from that. The point is to make things more interesting, regardless of morality. Not to "always be good" or "always be evil". In game this and other hostile noids will also hear through word of mouth that the players are traitors to humankind, meaning they will be more accepted in noid settlements (as a general rule, there can be exceptions, use your brain). This will also make the PCs wanted by human authorities.
3: Semi-Interesting, good: The PCs urge the shopkeeper to give in to the noids demands, and give them a subtle wink. Afterword some or all of the party leaves the wagon and tracks the noids to ambush them and get the goods and kid back. Maybe they do, maybe they don't. In this instance the PCs have the chance to piss off everyone and not get anything for it, but not end up wanted, which is the best outcome (full XP). If the kid dies, make a note and have the following happen: Have his ghost come back at a later date to haunt PCs. Have the shopkeeper hire a bounty hunter (or group) to bring the PCs down and drag them back to the shopkeeper so he can kill them. Make their be consequences to anything they do. If everything goes right, the kid is still traumatized by the incident, and stops talking. The shopkeeper and his wife give the PCs nothing for this outcome, they don't hate the PCs but don't like them either.
As you can see, you need to monetize your interest. That way players will try to be interesting, and get into interesting situations. They will be well on their way to being the best players you've ever heard of.
