Pay Attention to Paying Attention
It sounds simple, but one of the most important edges you have at the table is your awareness of what's going on. Who just raked a big pot? Who's stuck and trying to force the action? Who is ahead? Behind? Patient? Impatient? What bet sizings are your opponents using in different situations? Who is playing level-1, -2, or -3 poker? What range are you putting each player on? What line are they on? Are they playing a positionally aware game or not? What range and line are they putting you on? And so on. Remember that poker is ultimately a game of incomplete information. Your opponents are constantly trying to hide information from you. The action is continuous. Your fellow players are actively trying to deceive you. Look away and you might miss something vitally important. Remember, the first step to REDi is Reads. The hand ranges and lines you put your opponents on depend entirely on your ability to focus on the action and ferret out what little truths you can. This includes when you're not directly involved in a pot, which at a full-ring table should be a lot of the time. When you fold a hand, don't stop playing. Don't look away, or check your texts, or chat with the waitress; focus on the other players still involved in the hand. Put them on ranges and lines. Guess their hands. Look for tells. And most importantly, continually ask yourself if you're paying attention. If you're not, get up, take a walk, and then come back focused and in the moment. If you don't, there's no sense continuing to play. Your opponents are paying attention; if you're not, you're putting yourself at a serious disadvantage.
All-in for now...