Once a ticket is created, every communication about the issue should flow through the that ticket. Corresponding with a customer outside of the ticket makes it difficult for other team members to have context when reviewing the ticket. Request that customers please use the ticket system when corresponding with you in order to track requests more efficiently.

Documentation is a huge part of our culture. When we learn new things, we put them in the Autotask knowledge base or in IT Glue so everyone has access to the knowledge. This includes how-tos, specialty software a customer may use, frequently seen issues etc. Get used to searching for technical answers in the Autotask KB. If we've seen an unusual issue before, the solution will most likely be documented in the Autotask KB.
Similarly, everything related to a specific customer issue or concern gets documented in a ticket. Put notes about phone calls you've had with customers, unusual behavior, scheduling concerns, etc. in the ticket right away and update the ticket status when necessary.