Obtain one of the top tier pvp primaries. Preferably one that suits your playstyle, and has a quick time to kill. Learn everything about that weapon and it's capabilities. Never put yourself at a disadvantage, and always play to your strengths. When you become comfortable with this, then you can experiment with specials, find what fits your style more. You basically just get really good with one thing at a time, step by step.

Wall camp and use a shotgun. Follow around someone on your team that does well and kill whore. Use an annoying super like blade dancer or storm caller or hammer of sol. Use grenades that can get insta kills, like sticky grenades. Run away from gun fights you aren't going to win. Use a rocket for a heavy. These are all the tips you need to go well positive in destiny pvp. Basically think to yourself, "how can I play more like a little bïtch?" Then you'll do a lot better.