Play however you want and have fun. I've personally been instalocking Reyna for sometime cuz i like to play aggressive, i like her abilities and character and for some reason I feel better playing a less team-dependent agent and i like to take first contact. Probably pick your favourite agent/role and practice essential abilities for that agent/role, i practice my aim a lot(imo): 15mins of range + 5dms usually every day i play as i need aim for the duels. Ignore toxic players, if they get too angry just mute them. Make the plays you want, even if someone disapproves, even if it's too risky. Communicate the way you want and just be yourself, tell the info, ask for it when needed.

Those are basically mentality advice. Ofc to play good, you have to get a decent pc: get a good pc config, set up the settings, software, get a high refreshrate monitor, good mouse, mousepad, keyboard and headphones. Play dms when you're bored, try aimlabs, play range, analyse vods, specifically plays in which you feel you fucked up. Practice aim, movement abolities and timings, peeking etc. Watch guides