Thanks for the valuable input all, I think I have enough to go off of to improve. I'm also realizing that I need to find a good build/gun that I'm comfortable with, and that also it takes time to actually become familiarized with a gun itself. This is one of the things I really liked about the first Destiny. I do have some questions though, for improving armor/weapons (particularly weapons), is there a way to improve their base stats? That might be something I haven't delved into yet, but was wondering if I could make a gun masterwork for example, and add mods onto it. If so, do these improvements affect the gun in the Crucible at all?

Your recent game history shows Iron Banner, and both of your Guardians are [b][i]well below[/i][/b] the base 1550 that would be recommended. Stick to modes where the Light Level is disabled (read the particulars of each mode before you matchmake).

There’s a headshot multiplier in D2

Looks like you gave Iron Banner a try. It is a light level enabled PvP mode, so when you're only around 1500, going against a majority of players 1550 or above, it's gonna be a rough experience for most in that situation unfortunately. It means your guns do less damage to higher light players, so you are essentially hobbled while playing. You would probably find regular control to be a little better in that regard until you manage to up your light levels a little more.

You aren't toxic enough. Be more toxic then bungie will give you host advantage. At least that's how I think it works.

You are underleveled for iron banner. Play control. Ace should hit 70 for a ceit and 91 i think with memento mori active.

Pvp has quite a tall barrier for entry. I am no expert in crucible but if you are wanting to at least go in from time to time and have a more well-rounded time in Destiny here are some pointers that will hopefully be useful. Try to play with other people, you don't have to group up into a full team of 6, but playing with others will take the edge off and having some banter whilst you're playing helps. Try to lean toward more forgiving weapons until your confidence grows around maps, lanes and loadouts. 600 rpm Autos such as Gnawing Hunger with Kill Clip have reasonable times to kill and have ease-of-use on their side. You want to be enjoying your gaming time, not sweating your beans off landing a perfect triple tap with 140 Handcannons. Try playing little and often, whilst being prepared to call it a day. Pop in and play a match or two when you do log in to D2, and if you're not feeling it or if you happen to play against a nasty 6 stack of ungodly Flawless/Unbrokens back to back, just step away from crucible for the day. These tips may not make you a better player quickly but I wrote them with the aim for you to engage in pvp and enjoy it when you do. Work on what comes next later.

If you are massively underleveled when playing iron banner then exclusively use jotuun. Probably not a good idea to use hand cannons right away although ace is still top tier, I recommend rapid fire scout/auto rifles to pair with jotuun for now. Outside iron banner replace jotuun with a rapid/precision fusion. When you get better then go back to ace.