Studiometry has been a part of my design practice work flow since version 4. I have used it primarily to keep a database of clients, projects and invoicing. The software has been easy to set up, with the only exception of invoice and report templates that took some getting used to. The software has improved over time quite a bit, and the follow through on getting new features and resolving bugs has been very good, especially in the past few months. With version 6 estimating is becoming a viable part of the software for me, with the added ability to create itemized and highly detailed estimates. I would highly recommend this software for freelancers, one person studios and professionals in creative fields. The price point is excellent - compare $219 price tag with PrintSmith at a few thousand dollars. Additional seats do seem expensive, compared to the cost of initial license, but still very doable.

A few tips:
Overall:

Write out your work flow before setting up the software. Run a few projects in your mind and follow each step to see how the software may be of assistance or use during those steps.
Read help, watch tutorial videos. Really. There are a lot of features in the software, and it is one that is the backbone of the practice - so knowing obscure features could help a lot.
Make additional backups of your data files, template files to a CD or removable drive.

Invoice/Estimate templates:

Create your invoice/estimate first in a desktop publishing software to know all the things you need to include and understand the flow of it.
Print out a list of variables to have it handy when you are editing in visual template editor. It helps a lot especially when you are mixing text and variables.
Make backups of your templates you're about to edit through export feature in the visual template editor


Debt/Credit Categories:

Very useful when you have different rates for different clients, discounts, common expenses, etc - those are set up in Preferences in Categories.

Tech. Support/Bug resolution

Contact the developers - post bugs and questions on the support system - no other way they'll get resolved. I've used Studiometry support about 5 times in past few years, always to find resolution and quick answers.


Personal wish list:

InDesign plugin that would allow creation of nicely laid out and typeset documents with data from the program.
Trade/Barter billing setting would be wonderful, a lot of accounts that I have employ partial trade or barter and would be good to see which vendors you have credit with at a glance.
A more evolved system of discounts - percentages, automatically applied, etc.