Pick up calls or at least return them in timely manners.
We time plan and time manage properly to ensure we actually can keep our words.
And mainly realize we do not live alone on this planet and our actions have consequences.
Sadly, lots of people have no clue what I just said. They are disorganized, do not know how to plan, do not know how to say no and they do not understand how their actions impact others:
They are not aware that if they cancel meeting in last minute that they spoiled a chance for the other person to book clients, help them and make more money.
They don't get that person will never use their services in the future.
They don't realize that person had paying jobs ready to give them when they were supposed to meet and now they have nothing. Sometimes they miss couple of hundreds and sometimes tens thousands or more.
They don't realize that person will tell everyone else they know to be very careful to deal with this unreliable person, which logically means less business hence less money and as a bonus bad reputation.
And this is the best way to lose friends too.
So how about if you have problem with reliability, you think of the bad impact you have on others and also on your own life.
Take responsibility for your actions and very logically your life will start going in the right direction.