Press and leverage every early lead your team has:
This is something I see a lot of teams and players fail to capitalize on. Quite often, when a team can gain an early advantage in resources (territory, gold and active champions/personnel on the field), they need to leverage it to expand it and give themselves more room. Generally, this occurs when a team is able to hold items before the opposition. In the early game, almost all of a champion's stats will come from the champion's own stat scaling and whatever runes and masteries are active. Therefore, any item that can be brought into play will have a substantial impact on the stats of the champion relative to the "naked" champion at that point. When a team has just a few items and the other team doesn't, the percentage advantage in stats is much more significant than in the end game when teams are looking at similar items. Note, though that the introduction of the passive and active abilities of the endgame items can offset statistical advantages.
It is very important to remember that time is not on the side of the team who gains an early lead. The longer the match is continued after early leads are gained, the more resources the opposition can acquire to offset that lead.
Using lane pressure to affect enemy jungler:
This is strategy that I employ often while playing mid or bot to help control the tempo of the early game and is a strategy I do not often see utilized by other people. If your team has lanes that are weaker in sustain or more vulnerable and other lanes that are more robust and have better options for survivability such as high mobility, then the superior lanes should apply more pressure to draw or give more reason for jungle to show up.
It is imperative that the players providing the pressure are comfortable handling odd-man fights and ganking situations. Proper execution of this strategy can force the enemy jungler to split their time between lanes or have to cover the less-potent lane (for their team) rather than assist their stronger lane in gaining early kills or turrets.
Baiting and counter-baiting a gank:
Another seemingly understood tactic is the bait for ganks. In almost every match that I play, the attempts at baiting by the opposition are very poorly executed and tend to broadcast themselves to compromise. Sun Tzu once stated "Appear weak when you are strong and strong when you are weak". This may seem as simple as pulling back slightly or moving forward towards your target with low health. While this seems viable on the surface, such movements will generally cause reason for concern for your target if you haven't normally been executing those types of motion.
Take advantage of a pick-off or a single kill to upset the enemy team:
- Make it seem plausible: The best baits are the ones that appear to be a simple lack of oversight or a simple mistake. For example, if you're low on health and they stay in lane, it should be raising concern about your motivations. However, if you 'whiff' a skillshot or a cooldown it may not be as obvious that a gank is occurring. As an example, I may deliberately miss a skillshot just shy of my target to make it appear that I've missed my opening salvo in a damage trade. My opponent may chose to close in, knowing that I have one cooldown not immediately available for a trade. However, what is not apparent, is that I want to draw them in to allow my teammate to join and create an odd-man fight.
- Don't broadcast the fact that you know what the enemy team is attempting: In line with the taking a pot-shot at the enemy in the brush, many opportunities for a counter-gank bait are lost when the baiting champion takes a shot at the enemy. This broadcasts the fact that you know they're in a brush. This is more so for single-target skills rather than AoE shots. For example, if Vayne or Caitlyn fires their linear bolt/shot into a brush when there's only one enemy, it's a dead giveaway that they know of their presence. However, if there is a second enemy nearby whose presence is obvious (in the open or just moved into the brush) and the shot is fired at them, consequently hitting the ambusher's, then the knowledge of the ambusher's presence is not leaked.
Once you know that the enemy team is attempting a gank and they are unaware of your knowledge, then your team can set up a counter-gank to take advantage of the draw. However, it is imperative that you continue normal laning behavior with a slight focus on defense until your team is ready. When doing this, your team will need to set up quickly as the enemy team will not wait long to strike.
The enemy team had a straggler who your team has killed, giving your team an odd-man advantage. They key here is to quickly assess the situation and determine if your team has the resources (mana, health, and time) to pursue the rest of the enemy team and start killing them off. What this does is create a cycle of odd-man fights, preventing the enemy from getting a solid team grouping for the next minute or more, allowing your team to push and gain an even greater advantage. However, if the enemy team falls back, yielding territory or counter-pushing in a different location, then your team should not attempt to leverage the odd-man advantage through fights.
I have more strategies in a more comprehensive guide I've been working on over the months, but I'd like to keep my post relatively short and offer just some minor insight into my views on the strategy elements of this game.