I STRONGLY suggest you readup the features of the roms you wish to flash. You will get yourself into trouble if you don't do that. Do not just jump in to flash the easy way trying to follow some rules without understanding the features of the rom you wish to flash

The different roms in XDA has these features :

1. Some will wipe clean your phone while some will nbot
2. Some will auto root for you whiloe some will not
3. Some requires you to root it yourself after flashing using an insecure kernel method
4. Some roms required you to wipe clean ( ie factory/hard reset ) ; some will not - is optional step. But my advise is it is better to wipe clean ( hard reset ) so you start with a new plate , again is optional

I always recommend for new users, the easiest way of getting yourself started :

ROOT - easiest method use Supercurio

Rom flash - start with Litening - as using it , you learn how to use Odin. Also flashing this rom will NOT wipe your phone clean

Recovery - use Chainfire v4.0 . You will need recovery installed if you wish to do a nandroid backup and full restore of your rom. Some roms required you to flash using RECOVERY mode and not through Odin. Some roms even auto installed Chainfire recovery when you flash it

So the GOLDEN RULE is please READ the features of the rom you want to flash - check whether it use Odin or through recovery ??? Does it install recovery auto for you ?? Does the rom wipe clean your phone ??

Another GOLDEN rule :

ALWAYS ALWAYS wipe clean cache partition and in ADvanced mode - clear Dalvik cache BEFORE you flash a new rom - this will avoid reboots keep looping or phone fail to boot after flash. This also means it is in a way compulsory you install a RECOVERY first before attempting to flash a new rom. If you are lucky you could have a successful flash; if you are unlucky you will curse yourself because you want a fast way