Samsung GS4 VZW Rom Flashing topic

Hi, I'm new to Samsung devices and just got an S4 (coming from a Droid Bionic). It's the Verizon one (i545) on MK2 baseband. Do I need to use Safestrap or should I go with unlocking the bootloader via loki? I've tried flashing CM11 (cm-11-20140313-NIGHTLY-jflte) and CarbonRom (CARBON-KK-NIGHTLY-20140316-0428-jflte) with Safestrap 3.71 with no success. The phone boots into an endless black screen after the Safestrap logo.
I would appreciate any help on this or a link to what I need to do. My Internet searching has come up with either little or confusing information.
Thanks!