a trigger job on a glock could be anything from a polish to a full blown do everything.
99% of folks, robably like you would be just peachy starting off with a glock 3.5 connector, some sights, and then training.
to shoot well, you need to know what the trigger does, how it feels, what you need to do, when the gun fires, before, during and after.
Something smooth and reliable, like just throwing in a 3.5# connector and maybe a lil polish, will take you quite a ways until you ever feel that the guns holding you back.
Give someone a "hair" trigger, or something really light, is very much counter productive to your shooting progress. most folks will just slap away at the trigger without realizing all that needs to happen in order to shoot fast, accurately.
I can talk to you about slack, and walls, and overtravel, but until you get some either good training with a knowledgeable friend, or better yet, take a class, its just wasted info.