I enlisted in the guard as a 91B. What is the best way to build a warrant officer packet to be a 15A?

15A are commissioned guys. 153A is a the MOS for an Aviator applicant. The best way to build a packer is to go on the Warrant Officer recruiting website (google it) and download the sample packet and follow it to a T.

You can contact your Warrant Officer Strength Manager (WOSM) in your state who will help you with your packet. If you don't know how to get in touch with the WOSM, ask someone at your unit or a recruiter.

So as stated before, all packet information is found here. You should also utilize your chain to find a Warrant Officer Liason. They will help you understand the process and make sure you are a first time go. The recruiting website can also help you find a recruiter in your area.