Sage has a wealth of online training in their university offering.

Sage U has the very basics which everyone needs to know, but I learned almost everything beyond the basics with assistance from the Sage Partners I work for, who have been supporting Sage 100 for over 25 years.  Experience is so incredibly helpful to learn things behind the scenes on multiple customer systems (with a variety of enhancements and additional modules). 

Read all the Sage documents, and scour the help files for every screen you want to learn (to understand all the options).

For scripting I took Alnoor's class about 5-6 years ago which was a great way to start UDS work.

For being a data analyst, do your own reports / troubleshooting, from the raw data (not Sage reports).  Being familiar with the File Layouts, and how the data flows through the different processes is so important.

I second what Kevin said. I was as a senior accountant in '99 tasked with upgrading a large install of 3.71 for the whole 2000 big nothing. I went to classes. I documented and tested every function the company used, due diligence. Then they upgraded to Acuity (aka Sage 500). This was a 20 user distribution install, by the time all of this was done I had worked myself out of a job. Moved to CA to be a consultant. Read everything, work with partners, try everything.

I agree with Kevin and let your Sage partner maintain your install. It's a little late in the game to try and master 100 as it may not be around in a year or two.

Why did you say 100, may not be around in a year or two.

Sage is trending towards being a cloud provider. Desktop / legacy is at the end of its life.

What have you seen released lately as a new application for the Windows desktop by anyone? Everyone is maintaining what they have.

Sage 100 is not going away at all (mainly because I understand it is highly profitable for Sage).  It is also an incredibly feature rich platform that cloud offerings can't compete with in certain circumstances.  We are still selling / deploying net new Sage 100 systems, including in Canada (where Sage 100 does not officially exist).

The competition is niche (like pure financials for Sage Intacct), feature thin, or massively more expensive.  For sure it is aging software, but it is not obsolete.

On premise software is going to be required until internet connectivity is 100% reliable everywhere... which is not happening anytime soon. 

Until fiber is widely available going to a cloud platform is self defeating.

The best thing you can do at the moment is upgrade you local area network to gigabit hardware. If the end goal is the cloud running on 100 megabit will be a problem.

Fiber is widely available here, but nothing is 100% reliable.  I worked somewhere that a snow plow took out a utility box, where all their network connections were physically wiped out for days. 

With onsite computers and a backup generator they could keep their people working.

Before it got shut down due to the pandemic the Sage Summit was a great place to learn and meet people. I met many a tech and engineer from Sage there and learned a lot in the sessions.