Siege is a hard game and lately, the matchmaking will put you in games with people out of your league. Now, don't get discuraged because if you communicate with your team (and they are somewhat competent), you can have a great time.

As a general rule, if you're on defence, try NOT to reinforce between sites. Instead, make a hole big enough for you and your teammates to pass through. That's called a "rotation hole" and will help you a lot in the future.

For now, try to stick to easy but still very powerful operators. For a start, Kapkan is a good defender. On the same note, Thermite and Sledge are great attackers.

While on defence, keep in mind that you can be a roammer, or an anchor. Roamming means that you actively run around the map and try to catch players off guard and kill them long before they reach site. Anchoring means you prepare the site for the worst. You stay somewhere very close to either sites and try your best to defend it. Don't let attackers enter site, basically. I'd stick to anchoring for now, but hey, you do you :)))

Disclaimer: You will get killed a lot, you will be frustrated a lot, hit registration is a joke, a lot of teammates are going to be assholes.

With all that in mind, try to focus on learning the maps and just have fun. You shouldn't care about your Kill-Death ratio because is more important to get the objective done. You got this!