I've heard of mentees who started cleaning up construction areas on a flip at the end of each work day or picking up supplies at Home Depot and delivering them to the job site.

If I were you, I'd either find another company, or get a trailer and a helper and go pick them up yourself at Lowes or Home Depot.

For me that is one of the EASIEST maintenance calls I get.In addition, I will pick up some used washers and dryers locally off facebook marketplace for $150-200 and store them usually for when I put a new rental in service and need to put appliances in it.

As for picking a specific market - I would go after one with an increasing job and population growth.

Pick one or two markets near you and learn them inside and out. 

If tenant doesn't pick them up, then I auction the storage unit off.

Providing hand picked Comp Candidates to an Appraiser is an indication that the neighborhood Comps will not support the Seller's desired value, the Seller knows this and is trying to influence the Appraiser.

Especially in any place where you picked up the vocabulary employed in your post. 

So, no you can't pick a new stock and even if you want to talk active stock investing and picking individual stocks you're talking about lower on average returns because even most professional stock pickers don't beat index funds long term and have a greater risk of loss.

If you have the nicest property in the area, with some design features that will get people to stop scrolling through Zillow, and at standard, or touch above (given you have a really nice property) market rent, you will get to pick the best tenant.