Pause, pause frequently in real-time, you can still give commands to all your troops while paused. One thing which can be good or bad depending on situations is that agents take initiative unlike turnbased where its very much you have control over all the agents.
Also for grenades, im pretty sure you can set them to explode on landing, I usually set them for around 1.75 seconds as thats enough time to tell my soldiers to get out of there if its a mis-throw.
Pausing is the way to make your squad survive. The good thing about real-time is that you can do more effective squad tactics such as pincer movements, and you clear rooms far more quickly.
Just run it on slow time and you should be fine. One good thing about real-time is that you dont have to be there for the battle either. I can remember when doing a mission against a crashed UFO I had four squads guarding the only exit, had a sniper team at the far back, a machine gun team nearby and a heavy weapons (Autocannons) team close by and my raid team (just incase any aliens decide to stay in the craft)
I saved when they were all in position and then put it on fastest and left to do some....erm....stuff.
End result as I came back, lots and lots of dead aliens, no casualties on my part, a good mission finish.
k:
Another tip in real-time combat, when facing brain suckers, go into prone and they cant suck your brains, if you do it when they go-mid jump they fall unconcious on landing.