The most common way of styling your flannel shirt is by tying it around your waist. You can add a touch of street vibe to any of your OOTD looks just by wearing it this way.
If you want to go for a more boyish, laid-back look, just wear a simple tank top and button the collar of your flannel shirt. This style will look good with any type of bottoms.
For a more casual feel, just button up your flannel shirt and slip into a pair of shorts. You can either tuck the flannel shirt in for a more tapered look or just let it out.