I am currently available almost round-the-clock and will always agree a manageable "due-date" with a client, which I will never miss. I also keep in touch with clients constantly during a project.
I have a laptop, iPad and phone that all allow me to work on-the-go, and I have an excellent WiFi connection at my apartment and numerous good-quality alternative connections close by. My preferred method of contact is email as I am rarely disconnected from my email. I do also have Skype for more immediate interactions, and can provide a Thai phone number to contact me on for more long-term work. I prefer to keep my Facebook and other Social Networks for personal use.
I usually expect payment (via PayPal) within 3 working days of completion of the task at hand, and living in Thailand (where the cost of living is low) allows me to offer very reasonable/competitive rates for my services. I will of course negotiate on both of these, according to what is possible or preferable for each party.