To tighten clothes without sewing, one effective method is using safety pins for a temporary fix. Position them discretely on the inside seams to cinch in excess fabric without visible alterations. For a more permanent solution, fabric tape or iron-on hemming tape can adjust the fit of your garments. Simply apply the tape along the inside seams and iron to create a tighter fit. Additionally, shrinking clothes through washing methods, like hot water or a hot dryer, can help achieve a snugger fit. Always check fabric care labels first to avoid damage.