Even when you're just working a 9-to-5, you will find yourself in a negotiation sometimes. Not with a vendor, a client or a customer, but rather one with your manager about a promotion or a salary increase. These kinds of talks are often difficult and stressful and it's easy to get caught up in your anxiety and say things you don't want to.
One of the things that kept me back in my career progression was approaching these conversations in a completely wrong way. First I would state my case, but then an awkward silence would follow. I would then try to fill that silence with more words, which would often lead to me breaking down my argument and making it weaker.
To make this is a bit more tangible I will give you an example. Let's say I want to ask for a promotion. I would start off by saying something like "I've been working here for 3 years now, and I've been getting some really good results. I also got us that new client and I've been strengthening our relationships with our current clients. Therefor I believe I deserve a promotion to senior consultant". Then I would wait for a response and instantly I would start to ramble on, saying things like "but maybe it's not a good time because money's tight but it would still mean a lot to me to get this recognition".
What I've just done is give the other party a way out. I made my argument weaker by adding all these unncessary comments. I've also made it easier for the other party to say no because I've just given them a great reason to do so.
The best advice I ever got was from my manager at a previous employer. He told me exactly what I just explained and how it affects my bargaining position. He told me to just state my case and wait, let the awkwardness wash over the other party and sit there. You've just stated what you want and now it's up to the other party to come up with an answer.
Silence is a tactic that can be used to your advantage. It puts some pressure on the other party to respond and it gives you time to think about your next move. It also shows some confidence and assertiveness. It shows that you've thought this through and that you're not afraid to ask for what you want or need.
More often than not, this will only garner respect from the other party.