An emphasis on having a splendid appearance is sin (Prov 21:4, Moffatt). We are not to proudly display our physical appearance but to focus on our character (2 Cor 5:12, HCSB and GW with Wuest). We are not to be ostentatious and focus on being glamorous (1 Jn 2:16, Phillips). Likewise, we are commanded to not try to be conspicuous (Mt 6:1, Phillips). Not surprisingly, then, we are directed to avoid judgments based on appearance (Jn 7:24).
There are some negative results of focusing on appearance. First, since our appearance doesn’t matter to God because that’s not how He judges us (Gal 2:6, NET with TNT), our focusing on appearance shows we have different priorities than He does. See Mt 23:27. Second, emphasizing our physical appearance may cause us to live to make a good outward impression on others. This is wrong (Gal 1:10). Third, we will tend to become showy rather than substantive (Isa 30:7, Message), wrongly emphasizing charisma over character (Mt 7:16-18, Message). Fourth, an emphasis on physical appearance can feed sinful prejudice where we value lineage, race, or social station. Fifth, we may lie and hurt others to protect our image (Mt 14:9, JNTC note).
How may we avoid focusing on outward appearance? To start, we should beautify ourselves to the Lord by obeying Him (1 Pet 3:5). This would require us to avoid worldly ways of thinking (Col 2:22) by learning God’s way of thinking as described in the Bible (Eph 4:20-24). We would also need to remember that God looks at the heart – not at outward appearances (1 Sam 16:7).
Instead of being timid, learn to be appropriately bold.