What are best practices around tickets?

This is a good question, but the scope is quite large 😅. This can honestly be an entire course. Here's my thoughts stemming from my experience as a tech lead:

1. Match tasks based on level - As a tech lead, you should have a solid high-level idea of the technical complexity (depth) and scope (breadth) of the task, which should allow you to calculate a level (junior, mid-level, senior, etc). From there, you should make sure engineers get fitting tasks (e.g. you don't want to give a senior-level task to a junior dev). Things are a bit trickier as you should account for promotion paths as well. If a junior is gunning for mid-level, you should ideally give them mid-level tasks, not junior ones.
2. Establish ownership - There should be a theme among what tasks engineers work on, especially those at the higher end of mid-level or higher. You don't want all your engineers to work on A, B, C, D, and E because then nobody can become a strong domain expert on anything, which leads to ownership vacuums. For those more senior engineers, try to have 50%+ of their tasks follow a particular theme (certain product, certain system, etc).
3. Cross-pollinate - However, you don't want to create silos either where 1 engineer has 100% of their tasks in A, 1 engineer has 100% of their tasks in B, etc. That's why you want to make sure that engineers are constantly "dabbling" and working on new areas so they can get some working expertise on several areas. This makes your team more resilient, so that it doesn't collapse when a single engineer goes on vacation.