I usually attach streamers with a bit of masking tape. That secures it adequately while not pulling up paint on removal.
Any conveniently located surface will do, even the control surfces themselves. just make sure it can't get caught in the control linkages or the prop and that you maintain some sort of balance (If you put one on the left wing tip put one on the right as well for example)
Also I usually cut the streamer in half while it's still rolled up, so it's only half the width. A hack saw works fine for this, though you need to be careful.
I have a 3d-printed tool that makes it safer and easier, if I find the file for it I'll post it in the resource section at some point.
Start with a short piece of streamer, some 2-3 feet is enough, then lengthen it when you become more comfortable with it.
Be aware that the streamer induces quite a bit of drag so your motor might run hotter and your battery life will be shorter.
I've only streamer fought a couple of times with my son, and our MSBP's. I just tied a bit of mason's string around the landing skid and taped the streamer to it. We stretched out about half the streamer length and tore it there. Then we just rolled it up on the ground and threw the planes into the air, to let the streamers trail out.
It's an amazing amount of drag, but really cool to watch in the air!
I normally fit my streamers to a length of string which I then connect to a light rubber band. The rubber band is then wrapped around the tail wheel, the tail skid or taped to the rearmost point of the fuselage underneath the rudder.
The string is to get the target away from the rear of the plane. and provide a penalty of a string to wrap around the motor of any attacker who invades my space. The rubber band is a quick disconnect in the event that someone gets tangled up in the string so that the band breaks rather than ripping the tail off of my plane!
Works well and makes combat flying a little more demanding than just ramming the opponent.
Mind you with the KFM wings twin streamers are used and ramming permitted!