To have friends, you must be friendly. People are drawn to those who care. The rest are left to themselves.
No two people are exactly alike. So, do not expect to agree on everything. Those who cannot appreciate, would be better left to the company of a mirror.
The differences between people are what they bring to the table. One can provide what the other lacks. In such a way, friends help each other grow.
Opinions are irrelevant, since everyone has them. Agree to disagree and avoid needless strife. Whether one is right or wrong has no bearing on their worth.
That is not to say friends do not argue. Spirited discussions are enjoyable, so long as we do not stick our feelings where they do not belong. When everything is personal, nothing can be communicated.
In the end, a friend just wants you to be there. Sometimes, they need to talk and you need to listen. It would be a miserable world, were we left to the voices in our heads.