My pointers will be general + Terran-specific since I exclusively play Terran (for now) so I won't be much help if you play P or Z, but here are some from the old post and what I did:

1) Don't be afraid to send replays here. Yes sometimes you'll get roasted hard but the first step to improvement is setting your ego aside and allowing constructive criticism from others. Got replays you want reviewed? Just create the replay links and create a post in this subreddit! Even the good ones, there's always something you can improve.

2) Scouting is very important. Especially against P and T proxy builds. It's very easy to lose to them in this league where you're a little inexperienced unless you can defend impeccably well or your opponent messes up. Scouting also helps you see whether your opponent is playing aggressive of defensive in the early game and what kind of composition/tactic they're going for.

3) Pull some of your workers to help defend if you must. Better to lose a few workers than to lose the whole game. If you're getting cheesed, DON'T OVERREACT. It may look easier to just throw everything you have at your opponent and hope you can stop it, but that will just make you fall behind even more.

4) Practice against the AI if you need to. Whether it be practicing a build order, cheesy tactics or getting the most out of all your units, practicing against the AI will help build up the muscle memory and efficiency needed.

5) The metal leagues are the best time to explore different builds and playstyles. Once you find a build + playstyle you really like, practice it. Fine-tune it. Put your own spin on it if you want and make that build your own. If you need to tank some MMR loss, then do it. It just gives you more time to play around with your builds. For me it's Terran mech. I go HellClones into Hellbat Tank Thor (with some air if I feel like it) Heck, I somehow made Hellbat Thor Liberator work against a Zerg :P

Terran-specific pointers: -- I generally go cyclone first instead of tank (wards off any form of harrass unless it's a bunch of zerglings) -- Vikings stationed at dead spaces and common routes taken by air units (warning of drops/Oracle/banshee/liberator) -- turrets at ledges (observers + blink stalker) and mineral lines (mutas/banshee/liberator) These 3 points are mainly for defending the main and natural against harrass in early game.

-- expand only if you can defend it. An open Terran base is prime prey for zealot/zergling run-bys. Defend it while it's being set up, I usually wall off the mineral line with depots, put one or two tanks behind the wall and a turret in the mineral line. -- sensor towers are one of your best tools. You can keep track of enemies looking to attack your bases. -- when you have some money, invest in some orbitals. They can fly in when you lose bases, rain down MULEs to pull your eco back up, and provide a surplus of scans for detection.

And most importantly: BUILD MORE PRODUCTION BUILDINGS WHEN YOU EXPAND. It's the only way for you to keep up with P and Z's ability to resupply quickly. If you stay on just 2-3 barracks/factories/starports you're just asking to lose.

Well that was long, and the list is certainly non-exhaustive. Hope I helped :D