Just recently started playing sc2 and I was placed in gold, playing as zerg. I've been watching my replays and making the same mistakes. Those are the things I must work on myself but what are some common mistakes noobs make? Any tips?

Inject, remember to creep spread, and just keep on laddering.

play a fair amount of games, take a break watch replays make notes of what you did wrong. what you can improve and how to get from point a to point b easier, and more efficient,

Look up some build orders on teamliquid for each matchup
Learn safe openers where you can expand
Set some in game goals (10:00, 3 bases and 60 drones or 7:30, lair started 2 bases and 50 drones)
Inject, creep spread, drone, overlords, repeat

overlords and drones

Put a spore at your main and natural by 7:00 in ZvP and ZvT

go all in

MORE BASES
SCOUT
Use lings to check for how many bases he has. Leave a ling outside his base to see when he moves out. Leave lings at each watch tower.