For mediocre chess players like me I recommend trying online speed chess for a few months. Bullet chess where each player gets a minute total clock is a completely different game where you move every half second on average. Aggressive playing is rewarded - as long as you get your opponent to waste time thinking. The quick play allows you develop a better sense of positioning, game flow, and end game tactics. When you return to normal slow timed chess games after playing bullet for several months you will find that your clock management will be much improved.