This guide is made to help every team with their strategy and tactics, and who better to teach us than Sun Tsu himself?
all quotes are from his book the Art of war
however what is highlighted but not in quotations is my advice.
this guide is only about teamwork, this is also my first guide but considering that me and my ranked team have won 9 ranked matches in a row using these strategies and tactics I feel confident that they work when executed properly.

"avoid what is strong, attack what is weak"
alweays attack the weakest champions first, if 4 of them are in mid lane attack the 1 who's in bot lane etc etc

"all war is based on deception"
if you are going to attack make your
enemy think that you're on the defensive,
Decieve your enemy so they think that you're goin to do something else than what you
are planning, for example if you want to take the enemy blue buff in the beginning of the match
make your top champ "accidentaly" show himself in enemy red buff forest, making the opposing team think you're going for their red buff
instead of their blue.

Logisticts are more important than strategy and tactics
if you don't have any allies close and the enemy is numerous
no strategy or tactic in the world will work. make sure your team can get to and from plces fast.

"if you Know yourself and your enemy, you will not fear the rsult of 100 battles"
Know your strenghts and weaknesses aswell as the enemy chapions

Espionage and intelligense are key in any war
wards, wards and more wards, know were they are on the map so you can act accordingly
to where your enemy is and what they are doing. set up ganks and avoid team fights

Analys the terrain.
look for 3 things that are between you and your enemy, look for Distance, dangers (e.g a bush were the enemy team can gank you from) and barriers (walls).
use these for your advantage, for example if your enemy have more melee champions than you consider attacking through a barrier were they cannot get you.
If the enemy have greater ranged capabilities wait in a bush and gank them.
if the enemy team have greater AoE abilities than your team has divide them up by fighting them in the jungle for example.
there are many other ways to use the terrain.

"Confront them with annihilation, and they will then survive; plunge them into a deadly situation,
and they will then live. When people fall into danger, they are then able to strive for victory."
if your team are to spineless put them into a situation where they can't flee.

"It is essential to seek out enemy agents who have come to conduct espionage against you and to bribe them to serve you.
Give them instructions and care for them. Thus doubled agents are recruited and used."
if you find an enemy ward you don't have to destroy it, instead use it to give the enemy team misleading information.
e.g if you see a ward in the river close to the bot lane you can make the enemy think he's going for the enemy blue or the dragon.
instead move towards one of these and when you're outside the wards line of sight teleport to the top lane and gank, they won't suspect it.

"Hence that general is skilful in attack whose opponent does not know what to defend;
and he is skilful in defense whose opponent does not know what to attack."
if you've mislead the enemy team to thinking you're going to take baron or dragon they won't have a good defence against you taking the top/bot tower.

"Invincibility lies in the defence; the possibility of victory in the attack."
if you're team is good at defending then they will be nearly invincible, the defence will make you beat your enemy
but the attack (or counter attack) is what's going to win you the match.

“Thus the expert in battle moves the enemy, and is not moved by him.”
“One mark of a great soldier is that he fight on his own terms or fights not at all.”
make sure that your team picks the battlefield not the enemy.
don't chase after them into a bush for example, instead attack something that will force them to abandon their position (their tower for example) and
choose an ideal location for the teamfight between what you're attacking and the enemy. e.g if the enemy are mid then attack top tower and make sure
that your team is placed at a good ganking position between you and the enemy team. if they continue to push mid take the top tower and then gank them at
your mid tower.

"Do not repeat the tactics which have gained you one victory, but let your methods be regulated by the infinite variety of circumstances.”
don't use the same tactic for every team fight, you have to keep your tactics varied.
e.g if you lure them into a gank at baron they will not fall for the same trick again.

"if the command isn't clear and isn't followed then it's the fault of the commander, if the plans are clear but aren't followed it's the fault of the subordinate.
make sure htat your commands are clear to your team, if they are clear and they don't execute them it's their fault, if they aren't clear it's the commander's

“Victorious warriors win first and then go to war, while defeated warriors go to war first and then seek to win”
those who win team fights know that they already are going to win because of the advantages your team has (don't become arrogent)
the ones who enter the a teamfight but know that they can lose will fail.

“Supreme excellence consists of breaking the enemy's resistance without fighting.”
the best victories are those were you suffer no casualties, e.g if you destroy a tower or inhibitor or execute an succesful gank without anyone on your team
ending up dead or having to return to base to get mana and health.

“Even the finest sword plunged into salt water will eventually rust.”
even if you are vastly superior to your enemy you will eventually lose if you don't take advantage of it.

Learn from your mistakes
Despite what most people think, LoL matches aren't won or lost soley because of one person.
instead of blaming people for what they did wrong look for what mistakes you did.
once your sure of your mistakes make sure to not do them again, LEARN FROM YOUR MISTAKES