4.2.1 Untethered steps for iPhone 4 on 4.1 with 2.10.04 baseband

[mpapaj]

I don't necessarily need to preserve my baseband, but I'm thinking it's best if I ever decide to sell it.
My iPhone is currently jailbroken on 4.1 and I have my 4.2.1 SHSH saved in Tiny Umbrella and Cydia. What's my best plan to upgrade, jailbreak and keep all of my current apps and settings?

[bondkt]

appback - backs up appstore stuff

pkgback - backs up cydia stuff

(both aval in cydia)

use PT or TU to keep your BB.