I have been following this to some degree for a while, I will try to provide a list of major topics, key figures, locations, etc., so far involved in the whole affair. The whole thing is complicated, has been going on for a while, and can easily induce information overload leading to major leads being dropped, buried, forgotten, etc., newcomers to the investigation being unable to get a coherent picture or missing out on key details and information, and even some who have been following the issue as best they can missing out on some major leads just because there's so much going on. I'll list what I know which definitely isn't everything. As more comments come in a get upvoated I'll add to this post with edits. Hopefully this can serve as a roadmap to help you get your bearings and allow people to focus their digging on major figures and topics without retreading old ground.
Places:
Comet Ping Pong - Logo resembles FBI listed pedo symbol for "child lover", frequented by DC elites, Podesta emails confirm he and other DNC operatives have used the restaurant as a meeting place on several occasions, Obama held phone banks here in 2012 (or 2008?), website advertises "bathrooms behind hidden panels" and parties for "adults, kids, or a mix of both", owned by James Alefantis.
Besta Pizza - Next door to Comet, symbol is FBI listed pedo symbol for "boy lover", owned by Andrew Kline, a Clinton appointed DOJ Human Trafficking attorney.
Terasol - Across the street from Besta and Comet, symbol on website is FBI listed pedo symbol for "girl lover", picture of Hillary Clinton in the restaurant on website mainpage.
Beyond Borders - next to Terasol, a group "working to end child slavery and prevent violence against women and girls in Haiti", many speculations that the Clinton's/Clinton Foundation's activities in Haiti are related to child trafficking (don't know if there's been any evidence, circumstantial or otherwise on this point, please post if you know)
Buck's Fishing and Camping - "sister store" of Comet, also owned by Alefantis, website mainpage has image of cake that resembles "boy lover" symbol and a candle suggestively placed in front of a man and inside a pink donut to look like an erect penis penetrating an anus.
DC underground - There is an abandoned underground streetcar tunnel running the length of the street where Comet, Besta, Terasol, and Beyond Borders are located, could be used for any illegal activities related to this affair, images on JimmyComet Instagram show underground construction happening at Comet.
Through the Storm Outreach Ministries: the only result for a reverse image search of the specific "girl lover" symbol used on the Terasol site, a "maternity group home and transitional living program" offering immediate shelter to pregnant and homeless youth, based South Carolina.
The Boum Boum Room - fetish club shown on James Alefantis's instagram.
Politics and Prose Bookstore and Coffeehouse - Next to Besta and Comet, don't know the connection to pizzagate but someone else should post if they know, I've just seen it mentioned many times.
People:
Tony Podesta - Brother of John Podesta, noted art collector in DC area, adorns his home with art referencing serial killers and depicting minors in sexually suggestive and abusive contexts, fits image identifying abductor of Madeleine McCann.
John Podesta - fits image of abductor of Madeleine McCann, wiped emails in days leading up to McCann's abduction, emails show he was traveling during the days surrounding McCann's abduction, attends "spirit cooking" rituals with Marina Abramovic, strange image featuring Podesta holding up both hands with "14" and a vesica pisces drawn on his hands show extensive scaring on fingers and a bandaid on the middle finger of the left hand (the finger specified for bloodletting in Marina Abramovic's "spirit cooking" ritual).
James Alefantis - Owner of Comet, listed as 49th most powerful man in DC despite being a pizza shop owner, Instagram account (JimmyComet), now private, contained many suggestive and disturbing pictures involving children, images of underground construction being done at Comet, images of empty metal room with comments like #killroom, #murder, and "just wash it down when you're done", many jokes about stealing or selling babies, images associating young children and babies with pizza, an image of a young girl taped to a table at Comet, pictures of gay sex clubs, etc..
Instagram account "Joshuaryanv" - Employee of Comet, account shows many images directly associating pizza with sex and with gay sex specifically, image of Marina Abramovic.
Other Instagram accounts - many other Instagram accounts who followed, commented, etc., in relation to JimmyComet and Joshuryanv were found to have similar content sexualizing minors, images of random kids and babies, etc.
Marina Abramovic - Artist and occultist, part of elite DC political and art scene, performs rituals involving blood letting, consuming body fluids, art revolves around animal corpses, use of blood, depictions of cannibalism, use of occult symbols, connections to Alefantis, Podestas, Joshuaryanv, (and others?).
David Brock - Boyfriend of James Alefantis, founder of Correct The Record.
George Soros: Plutocratic financier of political movements all over the world usually leading to the overthrow of governments and destabilization of nations, records show direct payments to Comet Ping Pong and James Alefantis.
Hillary Clinton: photographed in Terasol, accused in MSM publicized supposed "Guccifer 2.0" note of being "high preistess" of a dark occult order, shows multiple symptoms of Kuru (seizures, tongue lesion, pneumonia) , a neurodegenerative prion disorder acquired by eating human organs, letter signed by Clinton thanking James Alefantis for cooking at an event appears on JimmyComet Instagram account.
Andrew Kline: Clinton appointed DOJ Human Trafficking Attorney and owner of Besta Pizza.
Barack Obama: held phone banks at Comet in 2012, photographed by James Alefantis playing ping pong with a young boy at a "white house dinner".
Issues not covered in Places or People sections:
Twittergate - Large number of accounts involved in sharing CP found on Twitter (unsure of direct connections to Pizzagate),
Cheesebay - Don't know much about this. suspiciously high payments on Ebay for old hard drives tied to a location in Hawaii, some images of the location were shared.
WethePizza - Another pizza place. Saga over the last couple days of an OP on reddit claiming to have found some CP files in relation to this pizza place, said he would post proof, made up a lot of stuff about trying to break the encryption on some files he had, claimed his partner in investigations was killed, never delivered anything proving his claims, posted images of CP, currently regarded as hoax and/or honeypot by many, but could be legitimate.
"Fake news" - Propaganda newspeak term being used by the MSM to smear independent sources of information. Now deployed against Pizzagate in NYT article by Cecilia Kang defending Comet and Alefantis. Being used by MSM and politicians in open calls for censorship.