How should one give advice without being too judgmental or condemning the person receiving the advice?
The best way in taking that approach is to show him that you only intend good for him. Likewise, he should be advised in private if possible in shaa Allah.
Ash-Shaykh Muhammad bin Saalih al-Uthaymeen, rahimahullah, said:
وليُعلم أن النصيحة هي مخاطبة الإنسان سراً بينك وبينه لأنك إذا نصحته سراً بينك وبينه أثرت في نفسه وعلم أنك ناصح
“And it should be known that naseeha [i.e. advice] is to address the person in private between yourself and him since if you were to advise him privately between yourself and him, you shall have an impact upon him and he will come to know that you are a sincere advisor”.
لكن إذا تكلمت أمام الناس عليه فإنه قد تأخذه العزة بالإثم فلا يقبل النصيحةوقد يظن أنك إنما تريد الانتقام منه وتوبيخه و وحطّ منزلته بين الناس فلا يقبل لكن إذا كانت النصيحة بينك وبينه صار لها ميزانٌ كبير عنده وقيمة وقبل ذلك
“However, if you speak against him in front of the people, then pride may carry him off to sin whereby he wouldn’t accept the naseeha. And he may assume that you only desire to inflict him and to rebuke him and to put him down in the presence of the people. Therefore, he wouldn’t accept [i.e the advice given to him]. On the other hand, if the naseeha was just between you and him, it would hold much weight and have a great value to him and he would accept it…”.
[Sharh Riyadh Saliheen, chapter: Naseeha]
AbdulFattaah bin Uthman