The best way to ensure that she knows you're her leader is training, never harshness or getting all emotional. When you teach her manners and ask her to, for instance, sit and wait while you put her food bowl down (just for a few seconds) and then give a release word ("OK") which says that she can now eat, that helps show her that you control things that are important to her. When you want to give her a treat or toy, you can ask for a sit too. You don't have to do it every time, but give her the idea that without you, she wouldn't have these things.
Obedience training, teaching to walk nicely on a leash, sit, stay, come, down all reiterate this to her. You'll have a much better relationship with your dog when you obedience train her. It builds a working bond between the two of you. That's what dogs are designed to do....help man with his "work", while we help them by providing for them.
You shouldn't have problems with a dog as long as you're assertive and consistant...setting up rules for her to go by and motivating/rewarding for good behavior. Don't spoil her and let her have her own way when you want her to comply with you. If you give a command, make certain that you can enforce it, or else....don't give it at all. You can teach her to pay attention to you if you practice and make it a habit....starting out in low distraction areas. "Watch me" equals a yummy treat. (for example)
I encourage you to find out about positive training methods and use those. It makes it so much more fun for both of you than domineering, collar yanking, scolding kind of teaching. And it makes the dog more eager to learn. This link, following, is a good one to give you the idea of how positive training methods work and how you can get started. You don't have to use a clicker, but the distinctive sound it makes seems to make a difference to a dog. They hear our voices all the time and don't tend to pay as much attention or notice. This sound has been shown to reach a different part of the brain which makes it very effective. (according to some studies that I heard about 2nd hand) But studies or not, I notice more responsiveness from the dogs with it. Just make sure your reward is something the dog really really loves.
http://www.clickerlessons.com/index.html