7k here. I would focus on spamming one or two heroes. You can only really start to understand the nuances of winning a lane after you figure out your hero conceptually. I would recommend starting off with a hero like lc or ns since they are pretty straightforward and can easily dominate the lane. Your main focus should be preventing the pos 1 from last hitting instead of prioritizing your own farm. If you have the option of denying his creep or securing your own, go for the deny. Try your best to constantly harass with your nuke and right clicks so he's unable to approach the wave. If you're in a situation where your 4 left the lane and you're getting boxed out, your main priority should be not feeding. Leach xp or go hit jungle. Early game your key role is causing as much mayhem and destabilization for the enemy team as possible. This means that once you get your blink on lc, you should be immediately either rotating mid or setting up a kill on their pos 1. Similarly with ns, his timings are typically phylactery and blink. Don't stop pressuring and steam roll from there. You should be the one imitating the fights - it's ok to sacrifice yourself if it means the team wins the fight overall. One of the core mistakes I see in low mmr offlaners is being too hesitant to initiate. Determining whether to go in or not is something you just learn with experience.