My picks:
1. If you have Blofeld and Spectre back, then focus on them! Move their plan into the centre of the action - not Bond´s "haunted past". Make us feel the threat by actually showing it in its various stages. The meeting in Rome is brilliantly done. After that... a little show on tv screens? Some dialogue-heavy deaings with C? That´s it? C´mon!
2. Don´t let Bond go rogue again. If you want to show doubts within Mi6, then have M go rogue by secretly giving Bond a mission that nobody is supposed to know about.
3. I know, I know: actors like Fiennes, Whishaw and Harris are great and capable. But why do we have to have a name cast for their characters after all? Go back to the original way of casting unknown but great character actors, letting M, Q and Moneypenny only have little expositional scenes. I want to see Bond´s journey. Not his posse.
4. If you want to establish a family connection between Bond and Blofeld, then really do it! Don´t imply that you´re going all in... and then fearfully remove most of it. It´s still there - but it´s not worth the build-up.
5. Find a compelling reason why Bond is going to Blofeld´s base. Don´t just let him travel there without a real plan, endangering not only himself but also Madeleine. (Rescuing Q actually was a not too bad idea in the earlier draft.)
6. Don´t go bigger in the action sequences (I´m looking at you, plane action in Austria!) but smaller. A chase on foot through the snow would have been more effective and exciting.
7. More travelogue, please. If you actually trouble yourself with moving your cast and crew around, show Bond enjoy going there. Take more time to establish the locations.
8. Use the "L´Americain"-sequence not only for the character moments between Bond and Madeleine but show Hinx in hot pursuit even there. Heighten the tension during this draggy midpoint, don´t soften it. It looks as if you don´t have enough money for more.
9. Don´t go back to London for many, many films to come. Establish the mission there, okay. But then, stay away from it! It´s a great town, I love it, and Deakins knew how to shoot it. But it´s done, okay? Move on. And away. Thankfully, the Mi6 building is blown apart. So no more symbolic showdowns there, yeah?
10. To have Bond single-handedly shooting his way out of the base AND letting the base explode is diminishing the threat of Blofeld completely! I know that he can´t be shot by Blofeld´s people - but really, he has just been tortured... and he still has no problem running around and hitting every mark he wants to? Why wasn´t the SMART BLOOD used better? Let M use those data, go against C and employ a unit to break Bond free, and in the midst of the mayhem Bond may find a way to blow up the base after finding a piece of evidence or a way to sabotage C´s plan in London - but conclude everything here! Blofeld´s base is - like so much in the film - getting a great build-up - and then is wasted within minutes.
11. Don´t have every character be related to each other. Did Madeleine really have to be Mr. White´s daughter? Why not have her be an innocent woman working for one of Spectre´s outlets, not knowing of their criminal intent. When she finds out she has to decide whether to continue that or get her conscience on, helping Bond. I love Mr. White re-appearing in SPECTRE. But giving him a conscience, after his deviish cackling about having people everywhere, does not work for me, really. Suddenly he is concerned about "women and children"? As if these never were hurt by Spectre´s plans before? And to have Bond fall for the daughter of the guy who loved to rile him up about Vesper... well, Bond´s Bond, of course, but,,,
12. Don´t drain the colors out of the cinematography. Desaturation is fine only as long as it does not rule the whole visual concept. Makes it look like a tv show. Oh, by the way, the film version of SPOOKS actually looked way better, especially the way London was shot.
13. In general, don´t overload Bond with HIGH DRAMA that actually can´t really be forced in anyway. Okay, it worked for SKYFALL, but only because of Dench-M´s swan song. Bond is not Shakespeare because it doesn´t need to be. To have the cake and eat it does not work.
14. Sam Mendes has given Bond everything he can. Move on to someone very different. Shake things up again! Those Bond films have always been the best. Break with what has come before, don´t cling to it. Sure, it will help with the grosses. But don´t make the mistake of justifying what you´ve done by the money. People want a new Bond film again and again. They didn´t pay for a ticket for SPECTRE because they appreciate how it has been done. They just wanted a new Bond film.