How to improve quickly

So I have met a few friends who love to play chess but are stuck at below 500 elo. When I watch their games I feel that they can easily reach 1000 elo if they do these things, as they are not really bad at chess. First, play longer games. Beginners tend to love blitz (or even bullet) as they hate to wait for their opponents. However, it is this impatience that leads to their common blunders. Just by playing longer games and staying patient, they can really eliminate their blunders and skyrocket their elo. Second, always do blunder check before every move. Beginners only consider their plans, how they should attack, how they may have a tactic if their opponent blunders, aka playing hope chess, but they forget that their opponent has their own plans and resources in that position too. Just by scanning the board for defending pieces and tactics, and reducing frequency of blunders, your opponent will do your work for you, and make blunders left and right. Third, stop looking for brillant moves and sacrifices. Many beginners are inspired to play chess by beautiful games played by legendary chess players like Mikhail Tal. They always look for sacrifices, no matter if they have more attacking pieces than defenders, no matter if their opponents can simply take and be completely fine, no matter if there exists counter attacks or tactics. They get a rush of adrenaline from sacrificing their minor pieces around their opponents' king, hoping for that brilliant move in game review to praise their stroke of genius. Just play more solidly and your patience will be awarded. Fourth, stop playing unsound gambits. What I mean by unsound is that the opening is a one trick pony which relies on your opponents playing some natural looking moves that is in fact a blunder, hoping for quick wins against the unprepared. This may be fun and it may work at first, but it won't work as you climb up the elo, and you won't improve by playing the gambits. With these advice, breaking 1000 elo should not be difficult, as long as you practice chess daily for a few months.