Which kind of pencils should be used by a beginner for drawing? I am curious what people would consider a basic / standard pencil type to have in their toolbox for pencil sketching.

There are a ton of variants I see with different hardness/softness etc and I don't plan to do anything advanced just want to sketch things out but I feel like while a regular pencil is just fine maybe there is a common type that may be more appropriate to learn with.

If your answer is 'use a regular pencil until you feel it's holding you back' that's fine too, just looking for a little guidance.

Trying to understand how to see things differently (mainly perspective) as coming from a technical and CAD background everything I try to sketch comes out reflecting that.

Edit:
If it makes a difference I am used to drawing lines firmly on paper.  So based on my understanding a harder pencil may be more appropriate? Or maybe a softer one to teach myself to not try and stab the paper?
I am not an expert but here is what I gathered from my experience.

Pencil have different hardness rated as follow:

Harder (very light strokes) 7H -> ... -> 2H -> HB -> 2B -> ... -> 7B Softer (dark strokes)


Start with a 2B or HB to "draw" (contour, shape, ...) 
Then add a 4B or 6B for your first shadings (I would go with 6B to widen the range of shade you can achieve). Do the lighter tones with your "first" pencil and the darker with this new one.
If you want "real black" instead of the grey provided by graphite pencil you can add a charcoal pencil.
completed with 3B, 4B, 5B etc. depending where you think there is a value (grey level) you can't achieve with what you have.