You cant.
You unlock it by getting to 10th Prestige.
Nothing they are the first emblem you unlock.
2nd prestige
It is unlocked at level 69.
Call in 50 Pave Lows.
Ten Tactical Nukes to unlock the emblem.
by killing someone with a ten or more killstreak that's for the emblem
Holt theres a emblem like that? look on Google
you dont unlock it at a level you unlock it by killing somone right before they get a 10 kill strick and you will earn the pot leaf emblem
Kill 300 people who are still dazed by a stun grenade. You must be prestiged to unlock this.
Completing the challenges you unlock through the levels. Some Titles and Callsigns can only be unlocked after you pretige.
anything that you like, because its what you prefer, no what other likes, and in my opinion I would choose a gold skull title will be fine :), for emblem I like the nuke emblem, and you unlock it when you call in 10 nukes :)