Part 2 of the complete guide to Minecraft. 100% new player friendly.
No need for tutorials, here is a complete, up to date list of potions and how they are concocted.
NOTE: I'm not gonna list the potions which are unnecessary.
BASICS
Water Bottle + Nether Wart = Awkward Potion
This potion is the base of most other potions, used with other ingredients in order to brew them.

TIER I
Awkward Potion + Magma Cream = Fire Resistance Potion
This potion's effects prevent the player from taking any form of fire damage, be it lava, fire, or a Fire Aspect sword.

Awkward Potion + Golden Carrot = Night Vision Potion
This potion's effects neutralize the natural darkness of night, caves, or when underwater. Allowing the player to see clearly.

Awkward Potion + Ghast Tear = Regeneration Potion
This potion, based on it's level, gradually restores the users health until it's duration expires.

Awkward Potion + Glistering Melon = Instant Health Potion
This potion instantly restores 4 points (2 hearts) of health.

Awkward Potion + Spider Eye = Poison Potion
The opposite of the Regeneration Potion, this potion gradually damages the player until it's duration expires. Non lethal, leaves the player with at least half a heart when set to Hard.

Awkward Potion + Sugar = Swiftness / Speed Potion
This potion's effects boost the player's movement speed, with the bonus increasing per level.

Awkward Potion + Pufferfish = Water Breathing Potion
This potion allows the player to breath underwater until the duration expires.

Awkward Potion + Blaze Powder = Strength Potion
This potion's effects significantly increase a player's attack damage until the duration expires. With the bonus based on level.

Awkward Potion + Fermented Spider Eye = Weakness Potion
The opposite of the Strength Potion, this potion reduces the attack damage of the user until the duration expires. With the reduction based on level.

TIER II/REVERSED POTIONS
Fermented Spider Eye - turns most potions into their negative versions. With opposite effects. So for example, if a Fermented Spider Eye is used on a Swiftness Potion, it would become a Slowness Potion, slowing instead of boosting. If an Instant Health Potion is used with a Fermented Spider Eye, it becomes an Instant Damage Potion, dealing heavy damage instead of healing. And for some reason, using a FSE on a Night Vision Potion, turns it into an Invisibility Potion, allowing the user to turn invisible.

TIER III/BOOSTED AND LINGERING POTIONS
Glowstone - Increases the potion's effects by one level. So a Swiftness Potion would become a Swiftness II Potion, giving even more bonus movement speed.
Redstone - Increases the potion's effect duration, making it last longer. So a Fire Res. Potion (5 Minutes), will become a Fire Res. Potion (8 Mins).
NOTE: If you use one ^^^, using the other will undo it's effects.
Dragon's Breath - Turns the potion into a lingering potion, allowing it to be thrown by a player, and release a cloud of particles in which affects anyone near or inside it. Acquired by fighting the Ender Dragon, when it performs its Breath Attack.

That's it! Thanks for reading, and if this helped you in any way, please leave a suggestion on what tutorial I should do next! Thanks! :D