How can I better my chances of getting into a specialized unit such as WHCA, SFAB or 160th SOAR when it comes to being interviewed?

Treat it like any other interview in general. What I mean by that is do your prep on the organization, mission, structure, duty position, etc. Military interviews are not that different than any other type of interview - it's going to largely depend on the person you are interviewing with.

You can find dozens of websites giving you "Interview 101" type tips - Turn off your phone before you go in, keep your focus on the interviewer, don't badmouth units/personnel, etc. They all apply in military interviews.

Some of the key ones to highlight are:

Prior to the interview, research, research, research. Research the position and organization (e.g., mission, goals, etc.) and familiarize yourself with the duties, responsibilities and requirements of the position. Don’t assume you know everything about the organization even if you have experience with the organization. Always do additional research especially to see if there have been any recent changes.

Look through your evaluations that they would have seen and make sure you are prepared to address any discrepancies between documents and/or shortfalls about skills and abilities related to the position/organization. Make sure you know what's in your official file and ESPECIALLY what (if anything) you gave them a copy of when applying for the position.

Prior to the interview, conduct 'mission rehearsals' (i.e., practice interviewing). Take the time to research and review typical interview questions to help give you a framework for your responses. Again, the answers to the quest might be different in a military interview, but for the most part the TYPE of questions asked will be the same - Why this position? Why this organization? Why you instead of someone else? etc.

When being interviewed, don't assume the person asking the questions has any specific knowledge about your background one way or another (i.e., "they already know that because it's on my resume, so they must be asking something else" or "I didn't say anything about THAT, so they must be asking about THIS").

Be prepared to go though your entire background that you might have covered it previously all again if asked (discussed in possibly other interviews? might have been in documents you submitted previously? etc. - I've been called in to interview applicants with barely five minutes warning because the 2-star was called into a meeting), but if you have something that isn't reflected that you think they should know, work it into the conversation (e.g., "It's not reflected in my previous assignments, but we had a Special Operations unit attached for logistical support when I was in the 123rd Mess-kit Repair Battalion and I worked with them directly ensuring they had their weekly delivery of snakes to eat").

During the interview, you'll have to take your guide from them about how detailed of an answer they want. Listen carefully to the question and answer it as directly as possible. If you are unclear exactly what they are asking, ask them to restate the question if you need clarification. When you've answered the question, ask a follow-up to see if you gave the information they were asking for or if they want more details. After the first few questions you should start to get a feel for the interviewer.

Think ahead to what and how you are going to answer instead of relaying on "no problem - I'll just answer honestly when asked". As I said before, a given are questions about "why do you want to ..." for the position, organization, etc. Unless your answer is "Because I'm psychotic and this will allow me to take out my aggression on others legally", there are no 'right' or 'wrong' answers for the "why" questions (your motivation) - these questions are usually for the interviewer to get to know you a bit better and the segway into the other questions.

If there are potential 'technical' questions related to your MOS or the position, prepare your response and make sure you have the details right. For example, it would be a good assumption that you're going to be involved with nonstandard logistics (NSL) if you're working with special operators, so a 'technical' question might apply to the specific functioning of a 92A ordering NSL through the logistic system ("I" would never ask that question, but if the S-4 or the Supply NCO is conducting the interview, they might get more 'technical'). Again, be prepared for different contingencies (BTW, if you haven't looked them over, you might want to be familiar with ATP 3-05.40, ADP 4-0, and FM 4-0* .. do a keyword search of "special operations" in them to get a start).

Again, it largely comes down to preparation, conduct and follow through after the interview. The process for preparation is really no different than what the Army teaches you - research your objective and practice the actions you will be doing up to, actions on, and actions after the objective. Usually there's less firearm utilization during interviews though.

Look through other guides about what to do and what not to do during interviews - those will absolutely universally apply. If you frequently check your watch as a habit, take it off. If you have trouble looking people in the eye, practice doing so. If you were abducted by aliens and can't make it to the interview when you are supposed to, notify they as soon as possible that you're delayed or will have to reschedule. The list goes on and on, but it many times can be summed up as respect and proper etiquette.

I've conducted many dozens of interviews (as well as being on quite a number on the other side of the desk) and I can tell you never once has anyone ever done one of the standard recommended things you see on the civilian side - A follow-up note or email thanking me for the interview. I absolutely suggest you follow-through with this. It doesn't have to be some fawning statement or a thesis restating why you're the perfect person for the position .. just a simple thank for allowing you to interview as well as they taking the time to conduct it and maybe a simple comment if there is something you bonded with the interviewer over ("I'm glad I meet another fly-fisherman at Ft. Boondocks") if there was any.

The follow-up note is something that brings you back to the 'top of the stack' in awareness, especially if there were multiple individuals (that's why the 'bonding' reference, because you might be interviewee #12, but they will recall that you were "the other fly-fisherman").

Good luck!
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* AT 3-05.40 - https://armypubs.army.mil/epubs/DR_pubs/DR_c/pdf/web/atp3_05x40.pdf
* ADP 4-0 - https://armypubs.army.mil/epubs/DR_pubs/DR_a/pdf/web/ARN18450_ADP%204-0%20FINAL%20WEB.pdf
* FM 4-0 - https://armypubs.army.mil/epubs/DR_pubs/DR_a/pdf/web/ARN19602_FM%204-0%20FINAL%20WEB%20v2.pdf

Frame you thoughts around the type of unit for which you apply coupled with your particular skill set and MOS. Focus on brief concise responses, neat and professional appearance, leave personal ideology behind and speak to that of the organization.

Be honest and professional

You can't anticipate all the questions you may be asked, as these are three different specialized units. Once you pass the initial screening and are called for interviews, the interviews will attempt to gauge your suitability for the role and your ability to work in a HIGH-PRESSURE environment. You can expect questions that would assess your fit for the role, for example, questions about your experience, skills, and elaboration on any specialized training. You should have your articulation of these 'basic' questions down pat. You will be gauged on your ability to express yourself with excellent communication, clearly and concisely describing your technical expertise, and with examples of your leadership and teamwork abilities under pressure.
Secondly, do your research and understand the organization's mission, the roles they fulfill, and the challenges with their operations. This will help you align your skills and goals with the unit's needs. In this regard, it can be helpful to review any letters of recommendation (endorsements) from your superiors that were included in your application packet. Your superiors may have experience and/or have an understanding of these organizations better than you do at the moment, and they will make comments in their endorsements about why you are an ideal candidate for their selection. Just have a good idea in your mind of what your superiors are saying about you and be prepared to elaborate on any examples that support those comments.

Interestingly, I have written endorsements for Soldiers pursuing positions in all three of these organizations. They were selected because they were experienced experts in their career field, had tremendous growth and promotion potential, strong leadership qualities, and unquestionable loyalty and trustworthiness.