Be available, face to face or not.
The goal is to be in the right place at the right time. As much as nothing is better than being personally ready to help, you can also be useful in many things at a distance. If he calls you, pick up promptly.
Be a good listener.
Even though indirectly, your friend will try to communicate your problem. You may end up not realizing the need for it, if you’re busy being egocentric or cute. Pay attention to what your friend has to say.
Keep in touch daily but do not pester your friend.
Too many connections can irritate you. No matter how bad a person feels; knowing that someone cares makes all the difference.
If your friend seems resistant to your advice, stop offering them.
At some other time, he may be more willing to consider them. Or you may even prefer to find the solution for yourself. Anyway, the most important thing is to give moral support to your friend. Find out the best way to help.