It comes down to the individual player. One hit melee kills usually follow a burst from your weapon. Basically saying, you need to take down your opponents shields first. They don't have to be totally gone but you definitely want to deminish them in this
fashion. Grenades are great for taking shields as well as using a plasma weapon. Plasma repeaters, rifles and pistols are a shields bane in this game. Knowing the best uses for individual weapons will help you as well. Close quarter weapons such as the
shotgun, sword, hammer and assault rifle have little effect if you're not standing fairly close to your target. Although the AR can be used up to mid range if you happen to be good with it. Your mid-ranged weapons such as the pistol, DMR and the needle rifle
are the bread and butter for most players. The DMR is effective at long range if you've got the skill set. Long range weapon such as the sniper rifle are specialized. It also happens to be a power weapon. Power weapons can be defined as any weapon strong
enough to control an enemies movements. Lasers, snipers, rockets... even a shotgun or sword can be a power weapon in the right arena. You could also define a power weapon as any weapon that can deliver a one hit kill to a target.
It helps to know your environment. Get to know the maps. This is imperative to knowing where you're taking fire from and to then counter the attack with either evasion or counter fire. Without this knowledge, you're a walking dead man. Headshots come
with practice and quick aquisition. This should be your primary means of getting kills. Running up to an opponent for a melee is going to get you killed more times than not. If you're trying to rootout an opponent in a certain room or area, use grenades
to flush them out. At the very least try to take their shields down. After that, one shot to the head is all it takes. Granted, there's a lot to learn when you're playing a shooter but the basic strategies are the same. Having shields helps make up for
small mistakes but an experienced player will make short work of your shields, and the second they're gone, so are you.
The best way to play is with a group of people you can trust not to leave a match because you're losing. Folks are friendly for the most part and don't usually mind dropping a few pointers here and there but i wouldn't go into every match announcing the
fact that you're not that experienced. First off, you'll be painting a target on your back for the other team and second, you'll probably inadvertantly persuade some MLG try-hard to leave simply because his precious K/D rate could possibly suffer, leaving
your team shorthanded.
Anyway, this is turning into a wall of text so I'd better bring it to a close. My gamertag is Strunky. If you really want to learn, feel free to message me with a freind request. I'd be glad to help you learn the basics.