I honestly have very little ideas on how to improve the franchise. Hmm, perhaps a better way to gather resources, I know that Bioware is doing its best to get resource gathering to be interesting but the last two times have been kind of blah. On the other hand it's not as if I could do it any better.
I'd certainly like for them to keep the humour in the series. I always had fun when I found all the little shout outs to the other games (anyone that's got the "Master Thief" DLC knows what I'm talking about).
Hmm, perhaps my biggest idea is going to draw a lot of criticism but I think it's a good one. Okay, ready for blasphemy here: Shepard's gotta get killed. No wait! Think about it! One final blazing sacrifice of glory to triumph forever over the Reapers? Come on, that would be EPIC. Find the proper damn music for that scene and you've suddenly got one of the most powerful moments in the history of video games.
Ideas now for pure silliness:
1) Gray Warden team up!
2) The Shep's lovers have it out.
3) Sunglasses, why the hell does Shepard never wear sunglasses? S/He'd make that shit look good.
4) Normandy space battles! Actually wait, this is kind of a good idea!