Siemens NX (Unigraphics) Users

Did you look at the programs tutorials?

Or just "google" the following: Siemens NX constraint tutorial?

Youtube is your best bet. The Inferred option really works good at guessing the best constraint to use for a given application.

Check here https://www.youtube.com/playlist?list=PLQ140rIt4aOVkkf7MSY2UJPtge4lb3jT_

I know I'm about a year too late, but for anyone else in a similar situation:

If you already have some experience with CAD but have fallen out of touch, looking at tutorials might not be the way to go. Tutorials can get boring quite quickly even when while learning to use a tool, never mind while you're trying to get a refresher.

It might be a better idea to just grab some interesting looking objects around you and start modelling them. Could be anything - a spoon, your monitor, the chair you are sitting upon - the possibilities are nearly endless.

This way, you could choose to practice whatever you want - Sketcher, Surfacing or Assemblies. An added benefit is that you also build back some muscle memory for the workflows of the specific software that you are using.