One of the original Disney+ Rogue One: A Star Wars Story in the early days of the rebellion. It is far from the most anticipated title, but it is one that has so much potential to be a hit, just like the movie it is spinning off from was. That is, assuming the show avoids critical mistakes.
Star Wars TV shows have mainly been incredible thus far in the canon, with The Mandalorian especially getting a lot of love. For Cassian to reach those levels, it must ensure it does not make these detrimental, destructive narrative errors.
Contradicting The Canon
There have been a couple of instances where Star Wars TV shows have slightly altered or contradicted the canon established in the books or comics of the extended canon, and while this is fine for small, inoffensive things, it cannot be made a habit.
There is not a lot of canon content out there surrounding Cassian, but it still exists in the Cassian & K-2SO comic, and there is a ton of content covering the rebellion. Minor contradictions are obviously okay and mean nothing overall. But, significant changes can seriously harm the show to hardcore fans and alienate them, making getting involved in the deep, expansive extended canon lose its appeal.
Leaning Too Heavily On Fan Service
Fan service is such a tricky thing in Star Wars. When it is done well, it is incredible and should be loved by all fans since it is done for them. Being too reliant on it, though, can be a big mistake.
Star Wars is trying to move forward and create new stories branching out from the Skywalker saga. If Andor was littered with nothing but references, memes, cameos, and just overloaded with fan service, it would ruin the show. The right amount of references like this can enhance a project, and too much will sour many.
Overshadowing The Central Character
One of the criticisms many have launched at The Book Of Boba Fett is that it really does not focus enough or explore enough the character of Boba Fett. Given the title of the show, Andor cannot afford to do that.
A whole two episodes of this show not involving Cassian would be criminal and would rightfully be vilified by fans. The Book Of Boba Fett was structured like a book and so can be somewhat forgiven - especially since the episodes without Boba were so outstanding. However, this series cannot afford to emphasize everyone else over its titular character, though.
The Use Of Force s
If there is any show that could do without any Force s, it is Andor. Of course, if there is a story arc there and a real purpose for them that is executed well, the plot should include a Force using character, but relying on them would be a mistake.
This is meant to be a spy story focusing on Cassian and the early days of the rebellion. Not only are there few Jedi around at this time, but many of them are also hidden and are being hunted. The likes of Cal Kestis, Ahsoka Tano, and the Ghost crew could pop up, but they would most likely take away from the main cast. Inquisitorius may be a better fit, though.
Not Diving Into Cassian's Past
Cassian was established as a fascinating character in Rogue One thanks to his past, being a part of the fight since he was a child, and being a former Separatist. Rogue One did not develop his characterization much, but Andor needs to.
Being a Separatist turned rebel is not something that has come along often in the canon so far, making for some intriguing possibilities for Cassian's character exploration, from being a Separatist to his finding the rebellion to even encountering the in-between of the Galaxy (such as one of the powerful Star Wars crime syndicates). The show does not necessarily need flashbacks, but if season 1 finishes and audiences know just as much about his past as they did going into it, something has gone wrong.
Altering Cassian Into A Less Edgy Character
Forces Of Destiny is a fun little show so often immediately dismissed, but it has some great moments and unlikely duos. One of its worst aspects, though, is Jyn, who is presented as a far more basic heroine than what Rogue One gives viewers. Andor cannot do this with Cassian.
In that micro-series, Jyn acts totally out of character, with no edge. Now, it is the most childish of all Star Wars canon shows, so it can be overlooked, but it is still canon and did not really need to be. Cassian is shown to be ruthless and willing to do whatever he needs to do for the rebellion in Rogue One. That edge must be maintained; not only that, it should be furthered since this comes in the early days of the rebellion.
Not Leaning Into The Spy/Thriller Aspect Of The Show
One of the beautiful things about Star Wars is how it has the potential to branch out into so many genres, both broad and specific, from horror to adventure to romance to, in the case of Andor, spy thriller.
It is one of the most exciting things about the show. Fans have yet to get a proper, fully spy-type story told on-screen, and the series should lean right into it with double-crosses, espionage, and a ton of thrills and kills. Some fans may be disappointed if it is a very diluted, loose spy story.
Utilizing The Wrong Character Cameos
Some great characters are confirmed to appear in the Andor show, such as two of Star Wars' most underrated rebels, Bail Organa and Mon Mothma. Of course, audiences expect more familiar faces.
That can be a tricky thing for a show to pull off well. Black Krrsantan was a great initial fit for The Book Of Boba Fett, Fennec Shand was badass in The Bad Batch, but did Threepio and Artoo need to pop up in Rogue One? Having familiar rebels pop up, people like Saw perhaps, would be great, so too would Imperial officers who are around at the time, but if the show has the wrong kind of characters cameo, it could become subject to criticism from fans who just want an original story without recycled, fan-service-y appearances.
A Lack Of Stakes
One of the things that make Star Wars shows so tricky is knowing the fate of the characters. Every fan knows that Cassian, Mon Mothma, or Bail Organa won't be killed off in the show because they know how they die already, and that can take away from the tension and stakes.
Of course, stakes are not exclusively character fates, and the series has a variety of ways it can add suspense and keep fans on the edge of their seat. However, if the show puts Cassian in life-threatening situations in every other episode and threatens events that fans know cannot happen, the show will lack a lot of emotional resonance that viewers need to connect with the story.
Not Exploring Morality
Cassian's morality and the lengths he is willing to go to will likely be a focal point of the show. It should not just be his morality that's explored, though.
The moral grey area occupied by rebellion and resistance has been touched on in The Last Jedi, Rebels, The Bad Batch, Rogue One, and in the extended canon, and it must continue to be delved into here. Rebels cannot be painted as simple heroes just because they are fighting the Empire, because it is not the truth. Looking at the morality of the rebellion as a whole and regarding individuals like Cassian would add so much not just to the show, but to how fans view the Galactic Civil War.