Prepare for disconnects because this is still at potato level almost 2 years in. Dedicated servers for some custom games & Core vs. modes, T. hunt should have it now or in the near future (part of season 2's focus on updating the game but transparency has been off recently)
Everyone on Mic is welcome, sound is your friend as well as your cameras/drones (USE), when on defense - do not feel forced to hide in the objective room but do remember that's what you are protecting, You can team kill - try not to, Do not reinforce kids bedroom on the map house! ;)
You will constantly be learning new strats throughout and unlocking operators so I would say 50 hours is where you will feel as a graduate of Siege academy (Don't be put off, we've all been there!)
Stick to the standard for now as all operators can all be bought with in game currency, and all maps are free. I cannot recommend the second season pass as content was cancelled and others shunted back with little transparency causing quite a headache for all - Thanks OpErAtIoN hEaLtH, Poland died for this , #SaveTheMaps are the current buzzwords.
Situations will get you used to controls, then terrorist hunt for refining your aim. Siege videos on youtube may help you out too but stay away from the clickbaity one's ;)
Hope it helps! {-}7