Comprehensive Transmogrification Guide
First impressions are important. What you (or your toon, in this case) wears can say a lot about your character even before you say (or emote) anything.
Thankfully, Blizzard gave us transmogrification, so that we never have to look mismatched or out of place again when wearing our actual questing/raiding/PVP gear, without sacrificing useful bag space to carry around multiple outfits for our characters!
Below are some helpful suggestions of transmogs that will help you look more the part of a Sentinel soldier.
Please note: These are NOT REQUIRED (with the exception of the formal uniform when specified). Feel free to dress your toon how you wish!
Jump to a specific topic within this guide:
Sentinel Formal Uniform
Cloth Transmog Sets
Leather Transmog Sets
Mail Transmog Sets
Plate Transmog Sets
There are also quite a few other resources that you can use to outfit your character how you'd like. Many WoW sites (such as wowhead, wowroleplaygear, etc) have guides specifically for transmogrification. Another useful tool is Mogit. Mogit is an addon in-game that allows you to see all the different weapon/armor models on your character, mix and match them to make a set you'd like, and then share it with others who also have the addon installed.
Other useful links:
<Sentinel> Formal Uniform Code
Roleplaying Uniforms and Outfits - Battle.net Forums
Mogit Addon - Curse.com
Transmogrification Guide - Wowhead.com
This is still a work in progress! If you have any sets you'd like to see added, feel free to add a screenshot and list each of the pieces you are using and where to find them!