Starcraft 2 multiplayer 101 Part 1

This is for first-timer Starcraft player and explain basic things that will make you a decent silver/gold player instead of a "special" leaguers

Basics for having a good economy
-Unless you are in a late game, you should be constantly producing workers (drone, probe, SCV)
-You should try to have more bases than you opponent, and should not allow your opponent to get more expansions than you.
-You should protect your mineral line from harass from air units (phoenix, mutalisk, medievac drops, and more)  by having some anti-air units (stalkers, marines, hydralisk) near the minerals line.
-When you "forget" to protect your mineral line and harass is happening, pull your workers away from the mineral line and bring it near your army. While this will delay the mining, you will be able to save most of your workers. Remember, delay of mining is better than losing your workers.
-3 workers are the ideal number for each mineral patch/gas. In a average base with 8 mineral patch with 2 gas geyser should have 30 workers, you should constantly check the number of workers.
-If you are a Zerg player you should always have extra hatchery next to your main or natural

Basics for engaging enemy units
-There should be three parts of your army, tanking, damage and splash; tanking units are usually cheap units that can produced in mass and it's purpose is to absorb damage (i.e zerglings, zealots, marauder ), damage/splash units are units that are designed to dish out damage. Sometimes you would have separate units for damage and splash (i.e stalkers and high templar, or hydras and infesters), however if your micro is not good enough, you should get damage/splash units (i.e colossi, or siege tanks)
-You should always try to "time" your attack, against zerg player you should attack them right after their "drone" cycle because zerg use same "source" for army and workers. Against terran and protoss, you should attack them as soon as your upgrade finishes, if you are ahead of them even by slight lead in terms of upgrade, you would be able to over-power your opponents' army.
-You should always try to get your enemy out of position, for an example, you can attract marines away from sieged tanks and attack siege tanks with air units.
-Always try to get better position against your enemy, for an example if your opponent tries to surrond you with zerglings, go move your units against the wall or move into choke so your units have less "surface" to attack your units, this principle applies to any situation where it is melee units vs. range units and if you are attacking with mass melee units, you should try to surround your units to dish out most damage.
-When you are in a range vs. range situation, you should try to get a better concave against your enemy, this means that more units are attacking instead of lingering around back of the front line trying to find a empty spot in the front line