What exactly is map control? Map control is being able to control the map in a manner which allows your allies to roam the map safetly and disabling the enemy from doing the same. Getting towers also gives you more control of the map but in this guide I will only focus on the warding aspect.
Green represents that your team is winning, and pushing the enemy team right back to their base. Yellow represents an even game and red means that your team has been forced back to their base.
For early map control I usually grab 3 sight wards and 2 vision wards, I tend to ward the enemy red if they are starting blue and vice versa if they are starting red if my jungle is planning to invade. If the enemy jungle is a strong counter jungler (e.g nunu, shyvana, udyr, mundo, shaco, etc) or our jungle has a weak early (e.g amumu, naut, rammus, maokai, etc) who are vulnerable to invades I ward the buff they aren't starting at and alert my team to be ready to close in on the buff if an enemy is seen trying to steal it.
Blue Side Support
As the minions reach each other and the laning phase beings, remember to sight ward the area outside dragon around 2:05 or the brush further down along the wall (this is less safe but useful for jungles who can bypass wards outside drag by using gap closers to go straight to this brush and sometimes supports pink drag) to prevent ganks and begin to pink your tri bush around the 4 minute mark or when you see the enemy support move to ward your tribush, pinking the tribush is benefical in three ways, it allows your jungle to gank from there therefore allowing easy kills if they continue to play aggressive, the other benefical way is that it makes the enemy bot lane to play more passive as they will be constantly wary of ganks due to lank of vision allowing you to play more aggressive and make plays, the third is it also allerts you of ganks from the enemy jungler or enemy mid lane if they decide to take the long route passing through your jungle, increasing your chance of survival from the gank due to being alerted early.
Red Side Support
There is two ways of warding this lane, you can ward the enemy tribush and your dragon to stop ganks or just put one ward in between the two but that gives around 1-3 seconds less time for you to react to ganks. Usually pink your dragon unless you see the enemy support ward the brush along the wall then pink that brush instead to allow ganks from your jungle. If leashing your jungle at blue, NEVER EVER walk down via dragon toward your lane (remind your adc as well) as it can be very easy for the enemy bot to snag a kill or two as they have the advantage of brushes and you do not, getting killed early can allow the enemy bot lane to snowball, let it be your adc or you who gets caught it doesn't matter as the adc cannot 1v2 and will get zoned, if your adc gets caught then you will be forced to play passive or generally lose trades as the enemy bot lane will have more gold and be ahead in levels. It is possible for the enemy to gank from behind especially when you are low and hiding behind your tower and the enemy minions are pushed up to your tower or you are extremely pushed, these two situations could happen and putting a ward in the brush above your turret can give you 2-3 seconds heads up and could potentially save your life, always do this when you are being sieged and are forced to last hit at the tower.
For the bottom brushes, I then continue to ward the second brush once the support goes in there, it alerts you from initiates by the enemy support, when fights break out it also allows your adc and you to continue auto attacking, using spells which require vision and also lets you continue to aim skillshots with more chance of hitting due to vision instead of doing blind ones and relying on luck, warding the 2nd brush also alerts you from lane ganks by the enemy jungle. The enemy jungle will probably ward your first brush and try and stop you from initiating/free harassing the enemy bot lane hence you should use your second pink to eliminate the enemy ward, many people laugh when you take out their explorers but let them laugh as it prevents further wards placed and allows free action in that brush for 3mins. This stops supports like blitzcrank and thresh from landing easy hooks and grabs as they will be blind of your position in the bush. Buy an extra vision ward or two if you are facing champions with stealth like evelyn, twitch and rengar in the jungle or up against a twitch in lane so you can prevent ganks or surprise attacks from twitch, also make sure you aquire pinks when facing a vayne and they are nearing 6 as having vision of him whilst he is invisible can help you win the trade.
Global Ults/Fast Ganks
Ults such as pantheon, twisted fate, shen and nocturne which allow enemies to travel from a far these ults give you only a few seconds to react and are relatively hard to escape, if you see one of these champions on the enemy team, make sure you play with a more passive mindset than you usually do and as soon as you see them away from their lane walk back asap as their ults except for shen's ult have a radius which are not wide enough to be used from one lane to the other, they actually need to walk a certain distance (around 1/5th of the distance to the other lane) therefore giving you a few more seconds to react, you can ward further up or down from where you normally ward alerting you earlier as you'll see their ults windup animation but only do this if you are still wanting to play aggressive also this can save you from ganks such as rammus and hecarim who can reach and initiate ganks on you faster and usually come too fast for you to react and escape by the time you realise they reach your door step if you ward in the normal spots which work efficiently against other less mobile junglers.
Mid Game +
Either you or your jungle should always have an oracles on them (remember it no longer disappears on death), ensure you ward the map to control larger amounts of it and always remember to ward dragon and pink it if your team wants to do it in the next 3 minutes, baron should also be warded once mid game starts to ensure the enemy team does not sneak an early baron to gain an advantage, dragon spawns at 2:30 and baron spawns at 15:00 always remember to keep timers on dragon and baron so you can prepare and be there for the next one as it spawns (dragon respawn time is 6 minutes and baron is 7 minutes).
Helpful Videos (tips and tricks)
Warding Safetly Guide - http://www.youtube.com/watch?v=rTSKfdFl-OY
Bot Lane Positioning Mistakes - http://www.reignofgaming.net/blogs/a-different-view/emeraldw/25449-bot-lane-positioning-mistakes