However, if you have ONE brother, then the information about the shirt is not necessary to identifying your brother. Occasionally prepositions will throw you. When in doubt, check a handbook. A comma splice occurs when two independent clauses are joined only with a comma. A comma splice also occurs when a comma is used to divide a subject from its verb.
Tense shift Be careful to stay in a consistent tense.
Too often students move from past to present tense without good reason. The reader will find this annoying. Sentence fragment Silly things, to be avoided. Unless, like here, you are using them to achieve a certain effect. Don't violate this convention carelessly.