Here are some other bits of advice. Like I have said it's important to keep your troops in cover. If their transports are destroyed and a squad of Nurgle Marines are getting pounded then Go To Ground (Go To Ground)! That 3+ cover save means your opponent will be forced to focus fire on your Nurgle Marines in order to finish them off. Every IG unit that fires at this squad is taking heat off the rest of your army.
Obliterators deployed in cover are golden. Don't deepstrike them. Nothing is going to worry an IG player more than a squad of three mobile lascannons firing at their tanks and to be honest they most likely will not have a lot of options to directly deal with your Obliterators if you hold them back out of short range melta/plasma killiness. The deepstrike is a gamble and you are trading one expensive unit for one tank, it's not worth the tradeoff.
So now we move onto the end game. You have crippled the skimmers and deadly ordnance. Your opponent is bascically left with their command squads, veterans and psyker battle squads roaming the board in their chimeras. They still have the potential to hit you with short range melta & plasma but that's about it. You now have a strong advantage... Namely your flying princes! It's time to wreck their chimeras, lash the guardsmen and beat them in close combat. You will need to have claimed your share of objectives by this point and now you can shift from a defensive to aggressive stance. Guardsmen outside their chimeras are very weak so it's all about moving forward to control the other objectives left.
So that's about it from the perspective of going first. Next I will discuss how to win should you have to go second.