Parties are not necessarily wrong. Some parties can be quite enjoyable and in line with God's intentions. The real key to deciding whether to attend is asking yourself, "What kind of party is it?" If the parties you are referring to will be hosted by people who encourage drug usage or alcohol for minors, it is best not to go. Attending such parties can only lead to more difficulties or trouble for a young person striving to serve God.
Clothing is linked to our culture and is affected by current fads. Because God advises us to practice moderation (1 Timothy 2:9) and live holy lives (Ephesians 1:4), it is best that our clothing be modest and that it not be worn to draw undue attention to the person.
There are many clothing styles that are modest as well as attractive and functional. Of course, there are also clothing styles that reflect very immodest tastes and these should be avoided. Also, according to Deuteronomy 22:5, individuals should wear clothing that is typical for their gender (male or female).