Forum Discussion
First off, don't worry about your kill/death ratio - not only does Battlefield focus less on that than other titles like CoD, there are tons of other options available for you to become a great asset to your team (you can literally top the scoreboard with 0 kills and deaths for example).
You just need to find your niche; there was a time I was 2nd in Canada for knife kills and dogtags taken for example - I began to focus less on long-range weapons and turned to a more close quarters approach with higher rates of fire. @Real_Noobalishus is an ace pilot in the Pheonix league so he'll be your go-to for everything with wings, and there are tons of people on Twitter willing to throw in their two cents as well.
The single-frame deaths are a by-product of the weird TTK/TTD we've found ourselves in - basically, there was a back and forth on what people deemed balanced and now we're stuck; what happens to you also happens to other people so just make sure you shoot first and don't let go of the trigger until they are more than dead 😛
Biggest thing I can suggest is taking the time to learn the maps and their hotspots. When in doubt stick to your squad mates and never push until you're absolutely certain you are safe.
I'm extremely partial to the Lewis gun, the Model 37 shotgun, ZH-29, and my absolute #1 pick from BF1: the M1907 rifle for Assault class; you honestly can't go wrong with anything from the medic class (and self heals are great).
You can always level up your weapons in solo (or mp) Combines Arms at a slower rate if you are having trouble, and I suggest opting for hip fire routes on guns until you find your bearings.
Most important thing overall though is to just go at your own pace and have fun