How to give a colleagues constructive criticism without them going ballistic?

[thearchjoker]

I tend to be a bit too blunt sometimes, some people are used to it and work well with it while others tend to get really annoyed.

[Maybe_Maybe_not]

I have food for thoughts !
This issue has been addressed many times, quoting, synthesis:

Provide constructive positive feedback when possible
If you like something, then you should try to tell what exactly it is you liked about it. People enjoy receiving constructive positive feedback, and pointing out things you like is likely to encourage them to continue in that direction.

Provide constructive negative feedback when possible.
As long as you're constructive and carefully exercise tact when giving your opinion, then most people will take into consideration what you are saying.

If you don't have anything constructive to say, you should avoid saying it at all.
Nobody likes being told that their work sucks without a good reason why. Most people will take it personally if you just say something along the lines of "This was terrible!", because this is essentially meaningless and unhelpful and doesn't talk about anything objective.

If someone doesn't accept your criticism, you shouldn't force it down their throats.
If someone's decided that they don't agree with your criticism for whatever reason and has decided they're not going to change their ways, you can't really do anything about that.

Simple notions in psychology as well
Consider reading people's attitude through your observations of their behaviours and their personalities, switching seats mentally, adapting your speech to the person. After mastering all that plus 5/6 years of college, soon enough you will be a... Therapist LOL

[DrPepper12]

I was taught in my foundations and secondary ed classes to deliver a compliment sandwich when talking to parents about how their students are doing and with students themselves. Point to something they do really well that's related to the criticism. Discuss the criticism non-judgmentally by throwing it on them asking like what do you think you could have done differently? Were you feeling okay that day? Is everything okay at home? Did you use the resources I provided? You have to ask something innocuous to get them talking about what they see as the problem and then have them throw out solutions, and I mean solutions plural that way you can pick from them which matches their strength as you deliver the closing compliment. It really does work

[Dongie]

Well don't try to be easy then you'll get mad and take it out on them.

[exitseven]

Ijust tell it like it is. if they want to go crazy on me, I can deal with it.

[DrPepper12]

I wish. Gotta be diplomatic when dealing with parents and students in a school system.