I think we've all had a few unsavory characters run through our lives at some point, spilling coffee and stealing money along the way. It's normal to think back on all of the people that didn't stick with you and use that as a push to be thankful for the friends that have been by your side all along.
Unfortunately, it can be difficult for us to see when we ourselves are that bad friend. The one that everyone is just a little reluctant to text back. The friend that when your name lights up their screen they say, "oh man I'll just pretend I'm asleep and text her back later." I would venture to say that Every. Single. Person. has at some point been this type of friend to someone else. No matter what walk of life you come from, rich, poor, guy, girl, YOU were once the one someone jogged across a busy road to avoid.
It is human nature to think that the world revolves around us, and everyone else is just a supporting character to you, the protagonist. Avoiding this train of thought can be the first step to being a better friend and stop being "that guy." Remember that everyone feels like the protagonist, and try your best to be their support whenever you can. Do you have one friend that often offers to take a group photo of everyone else? Try standing in for her so she can be in the spotlight for once.
Don't only talk to people exclusively if you think they have something to offer you. Although it is important for a relationship, friendship or otherwise, to be give-and-take, people will take notice if you only show interest when they clearly have something on offer. If your friend you haven't talked to in five years makes a Facebook post about how they have a second ticket to that sold out concert and you really want to go, don't ask them if you can have it. They will forever remember you as the mooch and their trust in you will immediately decrease. This especially applies if you don't have a car. Don't let your friend with a car drive you everywhere, take an Uber and meet them somewhere! No one wants to feel like a taxi (unless they are an actual taxi driver, of course).
It's also so, so important to be an active participant in your friendships. Be mindful of how often your friends have invited you to spend time with them and try to keep up the pace by also extending invites out to them once in awhile. Being the thoughtful friend is way better than being the tag along friend. Eventually, the tag along friend becomes too much work to maintain and gets dropped from the group.
All of these little things add up and make a difference to those around you, whether anyone notices or not. Even if you think something nice you are doing won't make a difference in anyone's eyes, the things you do are helping every day to shape your character and allowing you to blossom into a more beautiful version of yourself. Don't be "that" friend that no one wants to hang out with anymore, and instead try out being the super intuitive friend with the warm glow around them.