#1 get rid of the entire idea of the Ancients and the Goa'uld. Reboot the whole series and forget the old continuity.
The Stargate movie isn't well known or particularly popular, there is absolutely no reason to stick with that stuff.
The premise is simple. The military finds a stargate of unknown alien origin. There is no need to go into the origins of it, at least not for a long, long time.
Our heroes go through every week to explore strange new worlds. Worlds with more variety than just reflections of ancient earth cultures (that's fine occasionally, but there was way too much of it).
More truly alien planets and beings to encounter, not just ancient humans and forehead aliens.
Ditch all of the stuff about humans getting starships. The humans should have the Stargate and the SMALL amounts of advanced tech they can occasionally get their hands on.
And keep the sense of fun. SGU lost too much of that. Perhaps SG1 was maybe a little TOO wacky at times. There is a balance to be found there.
There need to be at least a few likeable characters. That was another issue on SGU, I didn't hate it like some did, but it was trying to be way too grimdark and 99% of the characters were just unlikeable jerks.
Anyway that's my two cents.