There does seem to be many different ways to throw a nade. I was doing a mini-survival guide for CoD4 (aimed at new players), and I had a section devoted to nades, I may as well post it here for you to look at.
'Open, flash, and Clear'
In CQC and combat in general, it is important to have a solid flash/frag strategy. A good strategy, can save your arse, tip the balance in your favour, and it can intimidate opponents very effectively! AS RULE OF THUMB ALWAYS FLASH INTO AN UNKOWN AREA, OR AN AREA YOU SUSPECT THERE TO BE 'E'. Always flash into doorways and rooms that are near the epi-center of a gun fight, it could give you the tip if there is a camper in the room or a stalking 'E'.
Flash Defence
Flashes in COD4 are probably the most powerful 'nade in the game. Powerful for the effects they induce, and not the damage they cause, though a flash thrown near a guy who is 'red' can kill! Proximity is the key with flashes. The area effect of a flash is huge compared to other nades, and even those that thought they were out of range, can be momentarily disorientated. It is the disorientation (and presumed fear) that can be used to your advantage. When I first started playing COD4, I used to panic when I was flashed, I'd move, or shoot randomly hoping to snag the 'flasher'. More often than not though I'd be caught with my dick in my hand, and the guy who flashed me, would get an easy kill. There are a couple of strategies you can use to keep yourself in the fight, some are
If your sure of the cover around you, move towards that cover, and try if possible to keep your crosshair pointing in the direction the flash came from. If your not sure of the cover around you, hit the deck and go prone. Going prone gives you that split second longer to recover from a flash, and the sloppy shooter may miss you as he makes an initial visual sweep of the area you are in.
Flash back! this is a good strategy, but it requires you know the immediate vicinity that you are in. you always stand the risk of flashing yourself too, so this is a 'balls-of-steel' type manoeuvre.
Another way to survive a flash (even at close range) is to obscure the explosion totally, and that means the flash cloud too. I use this tactic often by going prone at a corner and throwing a flash, or by going prone behind low cover and throwing the flash the other side of the cover.
Flash Then Nade (alt nade then Flash)
I tend to utilise flashes with nades nowadays. If I know there is a room with 'E' in it, I will flash first, then nade straight afterwards. The initial disorientation will help your nade as all they will hear is the ping-ping. They may even suspect the second ping-ping to be another flash and do nothing - their mistake.
Airburst
Another feature I like about the flash grenade is its very short fuse. Its possible to throw a flash and have it explode before it hits the floor - this is how I do airburst flashes. I use airburst flashes quite often now as they can at times be more effective than ground burst flashes. Airburst flashes can disorientate, and there is little cover to be found from a flash going off over your head (or in your face). This of course makes this type of attack effective against targets behind primary cover, secondary cover, and even tertiary cover. Air burst flashes have to be thrown at acute angles for them to be effective, time and practice will nail this tactic.
Stuns
Stuns are identical to flash grenades, but instead of blinding, they slow movement considerably. Any tactic that you can use with flash grenades can be used with stuns too. The only thing that a stun cannot do is obfuscate. I don't like stuns for this reason. They can slow down 'E' to the point that any attack is negated, but stuns rely on the fact that 'E' might not be facing the same general direction as you are, and so they would have to turn to meet your attack. If they are already facing you, then your buggered basically, as running in is almost like running into a room without using any nade - suicidal!
Nades
Nades in CoD4 are awesome, they have a good area effect, and they momentarily throw up a cloud of dust and smoke that can briefly cover you assault or egress. There is not much to say about them, other than the fact that they can bounce off walls, and you can cook them.
Cooking Nades
Cooking nades is simple, pull the pin, and hold onto it until either, your bum hole puckers up, or it blows you in half. Anywhere between those two events is fine (there are challenges that require that you kill 'E' with cooked nades BTW).
Nade Bounce
CoD4 has a fantastic physic model, and that extends to the way nades bounce off objects in particular walls. I regularly throw nades 'around corners' using the bounce effect. It is possible to throw a nade around two corners if your in the right position and your aim is true! Think of how a pool ball bounces off the cushions on a pool table, that's how grenades bounce. the entry angle is equal to the exit angle, and that applies to the height at which the nades bounce off the wall too. bounce it higher up the wall, and it will travel further. Of course there is a sweet spot for this tactic, and you know what practice makes don't you? yeah, you got it!
Tweaking Nade Trajectory
Your can tweak them either before you throw them or (if your quick) as you are throwing them. Tweaking is an essential part of my nade throwing strategy, and at times it can be helpful to alter the flight of your nade as you throw it (especially if your strafing or moving at an angle to the intended target). this skill takes practice, its not impossible, but you do have to be sure of when and how to tweak.
Defensive Nading/Distraction
Grenades, flashes and stuns can be used defensively as well as offensively. This point might be lost on the beginner, but it is important to understand that you can use grenades as 'temporary walls'. Here is an analogy I like to use.
Your no doubt familiar with American Football, a superb game of skill, that requires great team work. Anyway, The running backs job is to run up the field with the ball when it is passed to him. To do that he relies on 'blockers' guys that get in the way of the opposition, and aid him in his run up field.
Well nades can be blockers too. They can block areas that you can't easily cover, and they can force enemy troops to retreat temporarily (or stop dead in their tracks) and thus aid in your egress. As well as their use as temporary walls, flashes can be used as distraction tools that can be used to fool 'E' into thinking that there is a 'blind threat' nearby. I don't mean blind threat as in flashed, but blind in respect to the fact that 'E' might not be able to see the threat because of an obstruction (usually corner or something like that).
I hope this little nade guide has been useful, the secret is to practice and experiment with nades, there is a lot more you can do than you can think!
