letting things go

You’ve summarized the main things that would’ve prevented Anakin’s downfall but here are a few others things that would’ve prevented it

• Learning how to let things go. Anakin’s inability to cope with loss and his unwillingness to open up to others about it made him vulnerable to Palpatine’s manipulations. If someone in the order could’ve taught him how to deal with this then he probably wouldn’t have turned. Yoda litterally told him “Train yourself to let go of everything you fear to lose”: This is something Anakin was incapable of doing because he was never taught how to do it in the first place and Obi Wan was somewhat dismissive of Anakin’s emotions so he didn’t do a good job in this regard either.

• Maybe if Fives was able to properly explain the full story to Rex and Anakin the Jedi order would’ve launched their investigation into Palpatine sooner before Palpatine was ready to launch order 66.

• Obi Wan and the council trusting Anakin with the truth of Obi Wan’s undercover bounty hunter mission. I can’t state enough how much the council and Obi Wan did Anakin dirty in this arc. They all know how volatile Anakin’s emotions are and they took advantage of that and withheld the truth from him until there was no other choice but to tell him. This enormous display of a lack of trust made it so much easier for Palpatine to convince Anakin that the council didn’t trust him. Heck, they made Palpatine’s case for him.

As others have said, the main reason Anakin joined the dark side was his inability to accept that everything is short-lived. Death and loss are part of life but Anakin didn't want to realize that. He wanted to find a way to avoid experiencing loss, seek power that could prevent him from having to endure loss. And since that's not exactly what the light side offers (everybody dies at one point and rejoins the Force) he thought it's the dark side that could offer it to him.

So, yeah, what Anakin needed to learn was to let go of his fear of loss, to accept that everything is fleeting which in turn would have made it easier for him to accept eventual loss. As you said, maybe Qui-Gon would have been able to teach him that properly (although Anakin actually learnt about this particular lesson from the Jedi, anyway, one way or the other). However, I think the choice of teacher is less problematic than the age of being taught. Anakin was already attached to somebody at the time he was brought to the Jedi Order. I think what could've helped prevent him from falling to the dark side, what could've helped him learning to implement the teaching about letting go of attachments is being brought to the Jedi as a toddler. So he would've grown up implementing this teaching in his life without being distracted by already existing attachments (that would've at least decreased the chance of him being incapable of letting go of attachments and falling to the dark side, I daresay).

^Regarding the Rako Hardeen-affair: On one hand, it's understandable that Anakin was hurt by that apparent lack of trust. It's a natural reaction. On the other hand, Anakin wasn't the only person close to Obi-Wan they didn't tell about the latter faking his death. Ahsoka, Cody, and Satine weren't in on the secret, either. So, although that course of action was indeed not really considerate, I don't think they focussed on withholding that secret specifically from Anakin. I think both sides had reasons for their actions/reactions but you are right that this affair made it easier for Palpatine to convince Anakin that the Jedi didn't care about him

Less sand.

I don’t think anything could’ve. It was his destiny. The only way for him to bring balance to the force is by being a practitioner of both sides.

@RoomOfFame No it isn't.

Elaborate.

@RoomOfFame It doesn't make sense to say that bringing balance to the Force means to practice both sides. If you serve the dark side you can't serve the light side at the same time and vice-versa. It simply doesn't make sense to support light side aspects like love and peace and dark side aspects like hate and destruction at the same time.

Not to mention that Anakin basically did what you suggest - as a Jedi, he served the light side while also relying on the dark side now and then which ended in him serving the dark side completely. He clearly failed to bring both sides in balance by using both of them.

Balance doesn't mean that you can use both the light and the dark side equally - at least not according to George Lucas. Based on what is shown in the movies and shows, balance means not giving the dark side power. The more you rely on the dark, the more you become out of balance. The more Anakin relied on his personal dark side (for example: by using his hate in a conflict), the more he spiralled towards his downfall. And the same goes for on a more galactic scale: when darksiders rule, the galaxy suffers. No balance anymore.

There is a Wook-user here who is an expert in this topic. I'd advice you to check out his essays, he explains these concepts very well: @WriterBuddha

The person we all know who cauld prevent Anakin from falling is Qui-Gon Jinn.

1. Using violence when nessary

2. Accepting his loss of his mom and his wife

3. Accepting that he is on the council but not the rank of master

4. Letting Mace Windu kill palpitine

5. Accepting that his apprentice is not of the Jedi order anymore

That is all I could think and credits go to @Optimusprimebumblebee "Neo Astral-X" 123 for number two.