How can I know when its okay to be brutally and completely honest and when I should be more "gentle" expressing my thoughts?

Be guided by the nature of the person you are speaking to. Some people prefer total honesty, but others would benefit more from careful handling.

This question can be difficult - most people would say that its something we have to sense! One way to approach this is to think about the end result: would the person you're talking to benefit more from stark honesty or a little more tact? It varies significantly based on person and circumstance but as a general rule, this has worked for me.

Tact and politeness are dictated by cultural norms and personal style. I personally would rather risk voicing an unpopular opinion and then apologize later for offending anyone...but that won't fly in the work place. It's good to know when to pick your battles. Sometimes being direct and incisive is the route of least suffering for everyone. Painful truths are better confronted than avoided. But ask yourself, do YOU need to be the one doing the confronting? And are you being brutally honest to save the person from additional suffering, or simply because you need to be right? Sometimes, it can be hard to know the difference. Thinking before speaking anything potentially hurtful is a good idea. It is also helpful to remember that some people are so in denial, they cannot be reached with words. Trying to confront, argue, and lecture people out of a strongly held belief (even one that seems ridiculous and false) is a losing battle. Whatever words you choose, you must be prepared to accept the other person where they're at, or leave them behind if you cannot.

just be as honest to yourself as you are to the other... we can say you would prefer someone to tell you that you dont look nice and it may be true, but not in a harsh way.. be honest but lay it gently to the person, like "you remember the dress you wore last week? i liked it better on you..." that way the person wont feel bad about their dressing but will know you dont approve of what they have on at the moment

I had the same problem myself, and sometimes still do in certain situations. Everyone is different and everyone reacts in different ways. Before you say anything, think about the situation and the person by standing in their shoes. Think, "What sort of opinions would I want to hear in this particular situation? The hard truth, or the more sugarcoated version. Neither of the choices are considered wrong, it just depends on the person you're saying it to.

Many times, it can take acute social skills that are attuned to what the other person is thinking or feeling. That, or really empathize with who you're talking to. Put yourself in their shoes and back, and make an objective decision about whether this person is hurting, and will ignore the truth and just see how much it hurts, or if they'll take it and do something with it, pain and all.

It is likely that if we build solid repertoire, have established empathy and then ask for permission, we can be more direct.

Take a step back and consider how the other person might feel. Truly engage them with empathy, asking, "How would -I- feel if confronted in such a way?" Being completely honest is always recommended, but when is it ever warranted to be "brutal" with somebody? No matter what, you should always engage others with honesty and kindness.

Honesty is important but being gentle and knowing when your honesty is being hurtful takes practice. Tread lightly and speak with kindness.

You should always be gentle and kind when expressing your thoughts. You should also feel free to be completely honest. We need honest feedback from each other, but it doesn't help if it is delivered in a harsh or cruel way. If you want to help, "speak the truth with love".