Always be transparent and under promise, over deliver.
A 'no' response is simply an opportunity to learn and improve; not a reason to give up. Simply move on to the next: this is a numbers game.
Keep moving forward, and you'll land on plenty of 'yes' responses.
Ask questions and remember to listen to the responses. Do not assume that you know what your potential or current client wants or thinks.
This one is pretty self-explanatory, but when we are feeling burnt out can go by the way side. It is important to know when you are off your game and reboot from time to time so you can bring your A Game.