Wucked :
Thanks Jay, I will try some of that out. I've been concentrating solely on assault class so far, and trying to play it like I did in BFBC2, so I probably need to work on some of the other classes a bit.
I often get frustrated watching guys run around the maps like loons, seemingly completely at random, and always coming out of it with lots of kills. I've always loved playing medic in the BF series and trying to support my squad, and while its fine for general point scoring it seems that this style of play isn't conducive to a good KD in BF3. Well, either that or its just me being useless. I'm also not very good at choosing appropriate weapons for the map. I tend to try and use just one weapon through all of them, so I guess I need to be more selective about which weapons and unlocks that I use. I think my favorite at the moment has to be the G3, but I do seem to die allot when using it.
Using Assault a lot will definitely not yield a high K/D unless you are just plain great. You are basically in the front line as cannon fodder. In vehicle maps I tend to stay away from Assault because you can't do anything about them. Assault is great for Rush or other game play. I do Assault sometimes if we squad up and we have at least one or two engineers in a Conquest map and be the medic as well as close combat situations. Assault is good for taking down engineers in a big Conquest map.
Alot of those loons use the thermal scope and flashlight to blind people. There are a lot of cheap tricks that people exploit. I don't feel right doing them. It's good to be productive in a squad that works together. I find myself changing squads until I find one that works for me. I would say you do need to adjust your weapons per map. I love the G3 with an ACOG on semi-auto. It's a good close distance sniper rifle. I've taken out alot of dudes trying to take me out and also snipers. However, on full auto it kicks and has a small clip. The rounds are larger to it takes less to take someone down, but you are reloading more. Also, reload when you can to make sure you have a full mag when things get hot. I always reload, hide and reload, kill, hide and reload.
As far as gun selection for Assault you want to determine the map and what you want to do on that map. If you want to hold a point down, the G3 is great in open areas. In closed areas I pick something with a bigger mag, is smaller, and faster to move around. Shotguns are good in tight areas. Also, you can sacrifice your medpack for a launcher if you are not in a good squad or find yourself laying around med packs alot already. Tubes can be very valuable in hallways and areas where enemy bunch up. Smoke is a good item to for getting past vehicles, even though its very hard to kill someone with it.
For Support you get sorta 2 types of LMG's, big ones with lots of ammo, or small ones that are almost Assault weapons. Either way pick the one that works for you. C4 is great for vehicles and the mortar is valuable at times for attacking or defending in RUSH. Take out snipers that sit still or groups that are spotted. You are a sitting duck though for other enemy mortars and snipers though so pick a good spot to set up shop.
Engineer.. already talked about blowing vehicles up. The SMG's range from crappy to pretty decent and on the lower side of assault rifles. They are good for close up, but not at any sort of range.
Sniper. Don't pick a semi auto rifle for long range shooting. Pick the longer bolt action rifles for distance and semi auto for mid to close distance. Also choose the right scope for the map. 12x for long range, 8 or 7x for mid range, and sometimes the x4 ACOG in small maps has advantages because it is alot of times one shot per kill.
bipod vs grip. Use the bipod when you are sitting and waiting for someone to come in an area. Examples. Long range sniping and looking around. Sitting in a hallway with a LMG for suckers coming down to death row. Used the grip for everything else that involves you moving.
Hope some of that helps.