i think many users don't know how they can automate the SCV (or drone or probes).

most of them wait for SCV come out, then click SCV to click on mineral.

what they can do is click on command center and right click on mineral, straight SCV come out it'll go mining already. works for vespene too.

other issue people face is the lack of supply depot. they forget to monitor that. using supply depot to block entrance is good BUT make sure you have surplus cos once that one's down you're short on supplies!

and also, some people like to spam marine in queue, not a good idea.

for initial stage, i go scv, then once i get more constant mineral intake i'll scv / marine in alternate fashion. after that once there's like 11 - 13 scv on minerals, it's marines all the way.

get vespenes for marauders and some upgrades too. ideally 3 - 4 scv per vespene.