Retirees, what do you know now that you wish you knew then?
#1 If you have not already done it finish your degree at least Bachelor's, if you have a degree attempt to get a higher one, i.e. Masters, PH D, JD, etc., most GS positions of any value GS-9 and above are so competitive now because of the economy and cutbacks and all the unemployed veterans won't even register you as being qualified w/o a minimum of a Master's.
#2 Get as many certifications as you can for the field you have an interest in going into especially since the military will pay for most if it is associated with your current job, if it is IT get all and every one you can, most companies in the IT field won't care as much about your degree in IT as they will about the certifications as they cost a great deal of money to get them.
#3 Try and ensure your clearance is as current as possible and if you can swing it even get it upgraded as most GS or contract jobs will require an active or at least one that has a few years still left on it for transferability so it won't cost them the money to get it done. If you plan on getting an overseas job, it will need to be current and active, so try and line up the job so you can roll into it while on transition, that way there is no break and it can be rolled over with ease.
#4 Probably the most important one I wish I had known, if you don't have a guaranteed job lined up to move right into before retiring, don't go, since you can start the process at almost two years out, start your networking and getting everything set up and lined up about a year out, if you are unable to do that, you may want to consider staying a little longer and moving to a new or higher position if available. The current economy is not very friendly to those getting out without a plan and job ready to go, and even those easy contract jobs around every military base are starting to dry up and becoming overly competitive, something that was extremely rare 5 years ago as there was plenty to go around, not any more.
That is the best offer, I am sure some of my other retirees and veterans have similar if not more in depth answers as well.
Make sure your medical documentation is complete and in order. It is of significant importance as you start your retirement physical to ensure every issue has been documented. This becomes tantamount to a successful VA claim.
Attend ACAP and use all the programs and assistance which are available. Create a Linked In Profile and start writing your resume. Make sure to contact the VA for VETS as they provide great service and support for resume creation both for Federal and civilian jobs.
Be prepared for the "slow down." As an infantry 1SG I am certain he is high speed low drag. The civilian world operates at a different pace.
That is an off the top of my head response. Good luck!
Late to the party on this one, but I would have informed myself to have a better mentor when I was a PSG...seems that once I made SFC and took over a tank platoon, the only one interested in my career was me. I pursued the pathways laid out/recommended for me as a 19K40 and tried to my utmost to ensure that all of my subordinates were set up for success in their careers, but somewhere along the way my superiors kinda forgot about looking out for me. (I know, comes across as sour-grapes and I digress....) I would also have probably told myself not to take the CSB at 15 years so that when I hit 20 and it was becoming evident that I probably wasn't going to be selected for MSG, that I could go ahead and retire at 20 and seek employment as a DA Civilian, to continue working for/with Soldiers. To any and all still serving, especially SSG(P) and up, ensure that those above you still have your best interests at heart and continue to do the right thing by those serving under you.
I can say that I did the right thing for my Soldiers/subordinate NCOs/peers and my officers, so that when I did retire, I had no regrets there at all!!
Kim, I think that the true excitement that comes from retirement is when you begin to realize all of the options that are out there: where you can live, industries you can work in, and occupations to chose from. I have a collection of a number of articles that I wrote for Military.com that describe the transition process. Above all, I think that you should discuss how much you have that is valuable from your military career and how you plan to give that back to society.
http://www.military.com/Opinions/0,,Storlie_Index,00.html