Buy a tent thats states it has an oversized bag like I did
Drop the tent, let as much air out as you can, make sure the door is open and roll towards the door, that way the air has somewhere to escape especially the ones with a built in ground sheet.
What do you blow the bed up with? I use an electric (12V) pump I bought from Wilkinsons for £7, there is an inlet and an outlet so as well as being able to blow the bed up you can suck the air out also, saves taking the hoover camping with you
I found it easier if you don't roll the sleeping bag up, just fold it in half and stuff it in, there that slippy if you roll it up you can't keep it tight while you get it in the bag.