Some of the most needed settings you've made already by registering an Helmdeck account. There is no need then to write your email or company name again. Although, depending on further usage, you should supplement and check what was already saved in Settings module. There are few things that can interest you:

For quotes, orders and invoices you need valid company name, number and address. Those will be visible to customers so be careful. There are also localization settings which influence all the users.

Continue current numerations for documents by changing their names, pattern and next number. You can also create multiple options for each document.

Add new bank and fill its details to make it accessible from documents such as offers and invoices.

Most of defaults are enough but you change names in select fields available in default system. Also make your own tags in here.

Add new users and manage their access to data and functionality by making permission groups.