I've started relearning chess after having played it a bit with my dad who learned from Microsoft chess. I came back and was ranked around 800 in December and have increased to around 1300 on lichess. Making sure to try to figure out what my opponent is wanting to do on his next move (to stop my own blunders) and learning the most common variations to an opening for each white and black contributed to a massive increase in rating. I imagine more focus on not blundering and learning some of the opening traps I tend to get caught in will probably get me to 1800 online.