A good Muslim should have firm belief in prophet Muhammad PBUH and Allah SWT. A good Muslim should be kind to everyone. A good Muslim should give zakat to the poor. A good Muslim should pray 5 times a day. A good Muslim should make a pilgrimage to Hajj if affordable. A good Muslim should fast during Ramadan and abstain from Haram. A good Muslim should have hope in Allah SWT when they are struggling in a deep trouble.
He is truthful, trustworthy, kind and generous and resilient.
A good muslim should have the best character; including obeying parents, being kind and respectful, etc. Someone who speaks good or stays silent. Not getting angry, having patience*; Be kind to your neighbor, guests etc. Someone who forgives. Prophet (SAW) said that, "Allah has revealed to me that you should humble yourselves to one another. One should neither hold himself above another nor transgress against another." Also one who does not self praise. One who does not hold on to his ego. Apologize when they are wrong, without arguing. Someone who isn't arrogant! Well basically someone with best character, modest, and believes in Allah (SWT), His messenger (SAW) and the Last Day.
Salam A good Muslim must have (1)strong faith by believing the 6 pillars of faith or iman believe in Allah thevoneness,angels,prophets,holy books,after life and qadar or taqdir of Allah(2)strong application of the 5 pillars of Islam: saying shahadah,performing prayer/salah 5 times a day in time properly,paying zakat periodically,fasting during the Ramadan and going hajj if he/she has capability to do that (3)obedience to Allah and taqwa so he/she will be humble,unselfish,trusted,honest,loyal,no... arrogant,always ready to help others or generous and maintain good relationship with his/her family,relatives,neighbors and friends