-It's unlikely although possible to get some scars this way. But I don't know if this is "automatic" or linked to "doing it wrong".
-Make sure you stop any plucking at the very least 1 month (ideally 2) before you start laser, or else you're definitely diminishing the efficiency of treatment (and thus wasting money in a way).
-Make sure you exfoliate, clean and moisturize really well, or you might get more skin problem. Might. For me though plucking a hair has always been a huge relief to weeks of pain from a repeatedly ingrown hair, and overall a temporary relief for my skin.