I'm not in the armed services - but many of my friends have been, I considered it before health problems ruled it out, and I come from an area of the country where service is extraordinarily common.
the rules for joining any military service -
1. find a friend who's served in that branch. They can be a good friend or just a friendly acquaintance who wants to help out a potential new member of their branch.
however, they absolutely CANNOT be a current recruiter or being rewarded for bringing in recruits right now. Moreso it can't be the first than the second, but either is dangerous. People who have recently honorably left the service are the best.
they will give you the straight scoop on the branch, where the bodies are buried, and how to get what you want out of the service while also meeting the obligations and responsibilities you signed up for.
the info you can get from Hacker News is good, but it's not a substitute for the real thing unless someone here with Coast Guard experience is willing to take you under their wing.
2. get every condition and bonus you want out of a recruiter and your contract IN WRITING. Just like a business contract in the real world, if it's not written down in your contract it's your word against theirs.
if a recruiter suddenly starts getting shifty and tries to weasel out of this, find another recruiter. There are lots of them out there, and the odds are good that one of them will give you what you want as long as you're reasonable in what you're asking for.
3. understand the phrase "the needs of the service" and what it really means. If you fail out of whatever school you get sent to, or otherwise don't meet the responsibilities and obligations of an armed service member in your initial training, you are going to get sent where the service feels like sending you since you didn't fully complete your part of the contract.
this tends to hit people who try doing crazy things like going straight into SF or SEAL tryouts without spending time in a combat arms branch, who then become a part of the very, very high washout rate for the tryout for these groups, and then get assigned wherever the service needs new bodies.
if you stick with a EE-related rating you should be fine since you already have skills there.
4. Remember that you can back out until you've completed all three of signing the contract, taking the oath, and reporting to basic training, no matter what the recruiters tell you. Talk to a civilian lawyer with experience with military law if you need confirmation. You'll have zero chance of ever joining the military again barring a draft if you back out after signing the contract though, and rightfully so.
you shouldn't sign the contract or take the oath if you aren't 100% sure you are ready and willing to serve, but if you have a change of heart, the military doesn't need people who aren't truly committed to doing their duty in this era of a volunteer force, so it's better you leave early rather than be a drain on the service.
5. Once you have taken the oath and reported to basic training, you are now under the UCMJ, not the Constitution. Adultery is a prosecutable offense in the military and you can still legally be shot by your own officer under a variety of interesting legal clauses if you don't do what you are supposed to in combat, however increasingly unlikely that is to happen in our current time.
there's a flip side to that as well. You also have no obligation to follow illegal orders given by your superiors, and in fact if you follow illegal orders (for instance, orders to commit war crimes) knowing they were illegal when given, you are considered guilty, "but it was an order!" won't cut it as a justification.
6. it's looking less and less likely there will be any significant US involvement in a conflict with Iran, but it's not out of the question Coast Guard boats would be deployed. The US Navy is aimed primarily at blue-water combat, and while it is increasing it's ability to operate in littoral/close to shore situations like the Persian Gulf, it has traditionally tapped Coast Guard boats and crews for expertise in that area.
For instance, a fair amount of Coasties served in Vietnam running boats used for littoral and river combat.
7. The one thing everyone I know that has served has emphasized to me - remember, when you sign up, you're agreeing to serve your country, not just ride the service for benefits and abandon things when they get tough. And no matter how desk clerk-like your job is in the military, there's a chance you will go into combat, and there's a chance you will die. Anyone who pretends to you otherwise is lying.