When someone is speaking with you about a problem, don't lose focus on the issue that is being brought up. When working with a large code base it can be very easy when another developer is trying discussing an issue, to start to think of something tangental. Try to focus on listening to the issue at hand, as well as what your response is. If you need to then you can ask for a moment and write down your thoughts on what has been said, and go back to focusing on the discussion.
Even if it's in your nature to regularly avoid disagreements, try not to avoid it all the time when discussing code. At times it can be very productive to express negative feedback when reviewing code, or disagreeing with a certain way something is written or expressed. Of course try to express yourself in a kind way, even when you disagree with something, however, if we never expressed our opinion when we disagreed with how something was written or put, we would also likely allow bugs or other issues to enter into our code.
It can be easy for us to forget at times that it can be difficult to decipher tone through written messages. Try to keep in mind that we won't always know the state of mind of the person we are trying to communicate with. We may want to try to write words to soften our tone or even emoticons to ensure that what we say isn't taken harshly, when being harsh is not our intention.
At times there will be misunderstandings in communicating with clients. At these times it can be beneficial to either arrange a meeting in person, or a phone meeting. It can be easy to ignore one email out of many emails that clients would receive, however speaking in person will make fixing things much easier.
While we of course will always have to talk about business and work, there are benefits to starting off a meeting with a casual conversation. There will be times where a client (non-tech members likely) may fear you will speak in terms they don't understand. They of course don't want to look confused, especially in a business meeting, and this type of anxiety can make a situation bad. Starting your meeting off with some informal conversation can help you make the client feel at ease, and set the tone for when you talk business. Additionally you may learn something about the client, which will help build your relationship with him, helping to give way to further business with them.
It's important to know who it is exactly that you will be meeting with. If the person you are meeting with is basically just a messenger for the person who will be making the decisions, then it is posible that what you say will end up unintentionally changed when it gets back to the "people in charge". This can easily cause a misunderstanding. Of course meeting with decision makers can be difficult, especially in a large company, however this is something you should make a priority. While this is very difficult, you should not expect less. This of course doesn't mean that every time you meet it should be with someone that's in charge, however you shouldn't only be meeting with a messenger.
Write a subject line that describes the content of the message, keeping it succinct and descriptive, but not overly wordy. For example:
Use:
Subject: BEAC-7155 - Need information to fix leak column
Not:
Subject: Blank
Subject: BEAC-7155
Subject: BEAC-7155 - Already finished fixing the battery level column, but I need some help fixing the leak column
Subject: Fix leak
Your reader should be able to tell the gist of the message you want to convey in the email, but the subject shouldn't contain most of the email by itself.
If you want to share information from a document with the person you're emailing, if they don't need to read through the whole thing, instead of attaching the whole document try to quote the applicable portions from the email for the person that you're emailing.
If you're emailing someone where spelling and how you put the content really matters then send a draft to a colleague to proofread your message.