I've found that some proficiency or familiarity with AutoCAD and/or Revit will open most doors (at least a little bit) for you as a "draftsperson" as you would be qualified as. Each firm is different though but if you have a good base to build off of you'll develop a lot of practical on-the-job knowledge as well.

Also, It all depends on what position you're looking to fill in a firm honestly. 3DS Max and Lumion software are your specialty rendering programs, which Photoshop is used to enhance the base renderings you produce there. SketchUp is a great starter program since it's free and used (largely) in the early conceptual development phases of a project.

Google and YouTube are fantastic resources for quick tutorials on all these programs.