Darth Lars said:

What I would do…

I would not take a crap on the EU, and on the EU fans. No matter what your opinion is on the EU, for decades the EU has been a huge part of Star Wars franchise and Star Wars fandom – some times a book or video game has been the biggest Star Wars event in that year.
I would take the fundamentals: the extended Skywalker/Organa family, Luke trained Jedi, there have been warlords and there is a sleeping Imperial “Remnant” out there – and leave almost everything else unsaid. Some events in books and video games could have happened: that should be up to the individual’s imagination. The new trilogy should validate – or invalidate – as little as possible.
The clean slate of Lucasfilm’s new continuity has angered many long-term fans. Instead, respecting that the EU exists would, I think, even help sales of older EU items (not that I have not seen a recent resurgence in interest for the EU, but it could be bigger) and help bring the original and sequel trilogies together.

But yes:

The new films has to be primarily about new characters. Not about the ones in the old films and especially not about the ones in the EU.

A new threat. And yes, it should involve the dark side, but it is unnecessary to have it be spoken out in the first scene that dark-side practitioners are behind it.

“Hero’s journey”, like Rey’s (in broad strokes)

Jedi are decimated. Not necessarily killed off off-screen until only Luke remains… before the movie even starts.

A locale with exotic aliens. Not necessarily a new cantina.

Han dies.

The end scene is an emotionally strong but slow scene with a wide-angle shot, but static, not circling.

And absolutely, no superweapon. No DS3. Period.

IsanRido said:

-Starkiller base ought to be a decoy, “These rebels will think we’re stupid enough to build yet another Death Shhtar!”. Ideally they could come up with a more clever way to be threating.

Interesting idea. Maybe the Republic would throw a large portion of their fleet at it, and then instead of firing – the planet or the sun explodes in a supernova, crippling the Republic’s military forces.
It would serve the same end as destroying the Hosnian system did in TFA but provide more opportunities for drama:

Lead-up to the fight, showing the tension before the battles. Like in ANH, ESB and ROTJ but which TFA lacked. Personally, I think those moments were very emotionally important in the original trilogy.

Fanatic Neo-Imp suicide-bomber type “pressing the button”.

The turning point when it has dawned on the Rep forces what is about to happen.

Remnant/First order officers when they understand that they have been led to die.

Show the aftermath of the defeat: people trying to survive. (also something TFA lacked because the planets just popped out of existence)

Remnant/First order propaganda after the event, blaming the Republic and cheering the “sacrifice” of the dead Neo-imps troops. That would show the ruthlessness of the Neo-Imp leaders.

… but yeah, some people would call that a rehash of ROTJ’s “It’s a trap” moment despite the new angles. 😉

Lord Haseo said:

As a mixed man I really don’t know how to respond to this but all I’ll say is that characters should transcend race. Finn for example doesn’t strike me as belonging to any ethnicity; to me he’s just a person.

Here here! Star Wars should stand above race-issues. White human, black human, green goblin, tall hairy sasquatch, crustacean, all on the same footing.
It would have been bold move if they had made Rey or Finn be another race than human - it would have been less practical with all the makeup but actors in TV-series seem to manage. I think they chose not to because they did not want to be reminded of the failure that was Jar-Jar.

BTW. Before TFA came out, I heard a rumour that the movie was going to show Stormtrooper taking off their helmets – and some of them would be of other races than human.

The EU is popular, but writing the sequel trilogy within its canon is creative suicide. It’s better to nuke it and have as much creative freedom as possible instead of having to worry about contradicting something in the Jedi Prince series. I know the EU has some gems, and you can still read those. They are still being printed.