These are just a few things you always avoid in handling with your precious Galaxy Ace to keep away into trouble and serious issues or end up your device in to fatal state like bricking it in no time. Many users have already learned about this stuff but this serve as warn to others to keep their Galaxy Ace stay as good as it is.
Do not install ROM Manager for Galaxy Ace
A ROM Manager is a manager for Clockworkmod Recovery , It Download and manage your ROMs, make and restore backups and make SD partitions. It's a very useful application which saves time because you don't have to reboot to recovery.
However , it doesn't support Galaxy Ace yet. It perfectly works on other Android Platforms but not on Ace. If you tried to install the ROM manger to your Ace , as a result it will not turn ON again and you already ended up a bricked phone. The only thing to fix it, is by sending it back to the service center nearest you. And then obcourse you will be charge for the fix.
So, Instead of using a ROM Manager, we recommend you to use a CWM Manager. Use Clockworkmod Recovery for Backups, Flashing .zip, Restoring and whatever the Recovery can manage to do.
Issues with Samsung Kies on Galaxy Ace to update the Firmware
Samsung Kies is an Official software application released by Samsung and use to update the firmware, sync your application and other stuff with the Samsung devices. According to some reports in forums that they used to bricked their Galaxy Ace while using Kies in updating the firmware. The problem is that it will just stuck and suddenly stops responding because of RAM issues. RAM or read only memory on Galaxy Ace does not meet for Kies requirements.
Those are just a brief details of some users report about how they messed up their Samsung Galaxy Ace. So, just let your Galaxy Ace untouched so that you can make use a lot of time with it.