iFaith Help

I was having problems with my jailbroken iPhone 4 on 4.3.1 so I saved my SHSH, synced with iTunes, restored the phone to factory settings, which updated it to 4.3.5, took it to the Apple store and they fixed it. This is the first time I've saved SHSH and I'm new to all this, but I did all this with no problem. Now I'm just wondering what to do next. The iFaith tutorials I find online only tell me how to back up the SHSH, and that's it, not what to do when you actually want to downgrade firmware. The thing is I know I'm going to have to restore from the backup of my phone on iTunes, use iFaith to downgrade to 4.3.1, and rejailbreak, but I'm not sure what order to do it in. Should I use iFaith first, then restore from backup, then jailbreak, or what? Anyone who has any experience doing this, I'd appreciate some help! Thanks in advance.