The Guild of Photographers is a friendly Photography association with a welcoming atmosphere and great facebook group full of knowledgable members. Their competitions are run to a high standard and you can join buddy groups and get mentoring to help you score highly in their competitions throughout the year. They are my person favourite Photography Association.
17hats is a super useful admin and crm software where you can keep track of your customers and their progress through your sales system. It allows you to file projects and paperwork under each client and links with your calendar, bank and much more.
Purpleport is a portfolio and networking site for Photographers, Models, Makeup Artists, Stylists, Photoshop Wizards and Tutors. They have forums, competitions and events you can sign up to and is the best UK sight for networking.
Square is a payment processor and website provider that's super easy to use. It allows you to take all types of payments, provides different point of sales terminals, lets you take payments on your phone and makes it super easy to set up items for sale to help keep an eye on stock and to see what your best sellers are etc.