The best way is to email me on hotmail.com (use rob_ainsley@).
You can try messaging me via Facebook, but for various reasons I often don’t see these quickly.
Phone calls usually don’t work for me, as I’ll be on my bike and won’t hear you above the traffic.
If you’re really, really keen on texting or WhatsApping me (for something important and urgent, such as you are commissioning paid work, my house is on fire, or Wetherspoons has a special offer on Thornbridge Jaipur) then you can construct my UK mobile phone number as follows:
0770 + (British emergency number for Fire Police or Ambulance) + 00 + 31.