Things you should know before writing a Next Gen. fanfic.
1-Harry married Ginny, and they had three children- James Sirius Potter, Albus Severus Potter, and Lily Luna Potter. Harry is Head of the Auror Department and becomes an Auror at age 17.
2-Ron married Hermione, and they have two children- Rose Weasley, and Hugo Weasley. Ron worked in Weasley's Wizard Wheezes for a while before becoming an Auror and working along side Harry. Hermione works in the Department of Magical Law Enforcement, under the Department for Regulation and Control of Magical Creature, working for elf-right and various other magical creatures.
3-Kingsley Shacklebolt is the new Minister of Magic.
4-McGonagall resigns her post as Headmistress, and by the time Albus is at Hogwarts, an entirely new Headmaster/Headmistress is there.
5-James Sirius' godparents are Ron and Hermione Weasley. Albus Severus' godfather is Neville Longbottom, and his wife, Hannah Longbottom, becomes his godmother. Lily Luna's godparents are undetermined.
6-Neville marries Hannah Abbot from Hufflepuff, who is also the new Landlady of the Leakey Cauldron, making Neville the Landlord as well. Neville is a Herbology teacher at Hogwarts.
7-Draco Malfoy marries Astoria Greengrass, Daphne Greengrass' sister. They have a boy name Scorpius Hyperion Malfoy, who will be attending Hogwarts with Rose and Albus. (Lily is close to Hugo's age). Draco Malfoy is grudgingly grateful because Harry saved his life, but they are not friends.
8-Luna Lovegood married Rolf Scamander, the grandson of Newt Scamander (author of Fantastic Beasts and Where to Find Them) and she becomes the wizarding equivalent of a naturalist. Rowling states that Luna is not completely crazy, however, and figures that most of the magical creatures her father talks about may not be real. She has twins- Lorcan and Lysander Scamander.
9- Edward Remus Lupin is a metaomorphmagus like his mother and doesn't inherit his dad's werewolf case. He's Victoire Weasley's boyfriend. Teddy is raised by his maternal grandmother, Andromeda Tonks.
10- Bill Weasley marries Fleur Delacour, and they have three children- Victoire Weasley (a seventh year during the epilogue), Dominique Weasley, and Louis Weasley. Percy Weasley marries Audrey (her last name remains undetermined) and has two kids- Molly Weasley and Lucy Weasley.
11- Vicotire Weasley is born on the second of May, the day Voldemort fell. Thus the name, 'Victoire', meaning 'Victory' in French."
12- There were conflicts regarding making a portrait for Severus Snape, but Harry fought for it to be made.
13- George Gideon Weasley marries Angelina Johnson, fellow Gryffindor and Chaser on the Quidditch team, and they have two children- Fred Weasley, and Roxanne Weasley.
14- Cho Chang marries a Muggle.
15- Dean Thomas is not actually a Muggle-Born, but a Half-blood. His father was killed by Death Eaters, and he had never told Dean's mother about his magical abilities. He never finds out about this.
16- Ginny plays professional Quidditch for the Holyhead Harpies, an all-girls Quidditch team, before retiring to raise her three children. She then works in the Daily Prophet, writing for the Sport's section.
17-Albus Potter is the ONLY one of the Potter children to inherit his father's and grandmother's eyes- an emerald green color.
18- James Potter II steals the Marauder's Map off his dad's desk.
19- Kreacher is the Potter family's House-elf.
20- Alice and Frank Longbottom never recover, and are warded in St. Mungos forever.
21-All, was well :)
-Thanks, and I hope this helped.
~The Amazing Slytherclaw