1. Think About Nationalities.
As much as we love the first movie, casting Frenchman Christopher Lambert as a Scottish warrior and Scotsman Sean Connery as a Spanish swordsman just seems lazy. Yes, they're great (okay, good) actors, but couldn't you find a good, young Scottish actor, or at least one who wasn't French? Or, God forbid, changed the nationalities of the characters? It's one thing to have to explain why Arnold Schwarzenegger sounds Austrian in every movie, but asking men with undisguisable accents (Lambert could barely speak English!) to play characters with completely different accents is looking for trouble.

2. Pick a Story and Stick With It.
Even though the first movie stated that Connor MacLeod and Juan Ramirez were born on Earth, the second movie decided that they were in fact aliens from the planet Zeist, and that they were members of a rebellion there before getting banished to Earth and being reborn as babies. (Which is fine, I suppose, but to be banished at the same time and get reborn 2,000 years apart requires even further ret-conning.). If they're mystical beings, keep 'em mystical; if they're aliens, they're aliens. I vote for mystical, though.

3. Don't Wrap Everything Up With a Bow..
After centuries of Quickenings -- the absorption of one Immortal's life energies and knowledge by another -- the first Highlander ends with the Gathering, when the remaining living Immortals on Earth kill each other and last man standing Connor MacLeod wins the Prize: mortality. ...Except the second film brings Ramirez back to life and brings more Immortals to Earth from space, and the third film frees some more Immortals who were imprisoned in a cave this whole time, which raises the question of how Connor won the Prize without finding and killing them. We get it -- you didn't plan ahead for any sequels. Plan ahead this time.

4. Beheadings Aren't For Kids.
If you're planning on keeping the Highlander concept intact, with beheadings being the only method of dispatching an Immortal, then you probably shouldn't develop it into an animated series, in which the Immortals stop fighting and rename themselves Jettators, and knowledge is passed from one Jettator to another not by beheading, but by "sharing." This is a real thing that happened.

5. Do Not Make the Highlander Sparkle.
Seriously, Summit, we've seen Twilight. We know what you do. Don't do it here.

What do you want to see in a new Highlander film?