Don’t lecture. Ask questions to get her to think. Explain gently. And don’t go too fast.

Patience. Try explaining a variety of different ways if she isn’t getting it. Be willing to both do a problem for her, and to give her time to work through other problems on her own. Remember some steps might be very obvious to you, but not to her. Let her tell you how she thknks about the problem, so you can point out her mistake in how she takes apart a problem.

Maybe she likes you? Like like. And, it’s not just a study date?

My experience is that good tutoring requires the tutor to pay an exorbitant amount of attention. It’s not just that you know the material, but that you know how your student is doing. You need to ask her how things are going in the beginning, but over time, you have to work our subtler cues. Her tone, the way she holds her head, how she sits in the chair will tell you whether what you are doing is working for her. You also have to figure out how to give her praise in a way that works for the situation and for her.

Most students being tutored want to learn. If you express frustration, that eats away at their commitment. So when things get tough, you have to accept it happily as the kind of challenge you want.

Oh, and make sure she’s talking about as much as you are. Ask questions if necessary, or let her talk things through.

Lots of patience and gentle explanations that don’t come across as being “superior”.

I swear when I first glanced at the question, I thought is said, “Any tips for torturing one of your peers?”

Hook her up to an electro shock machine and give her a ZAP every time she answers wrong.

That would fulfill the requirements of not being “condescending or dull”.

Depends a little on the type of physics newtonian is usually fairly simple but Einstein can be problematic because it doesn’t always conform to straight forward way of thinking.

But in general people sometimes get very hung up on (and intimidated by) the equations. Some very useful advice I got was explain it to them as statements; take F=ma. What is that? Force equals mass times acceleration. Sometimes seeing it spelled out helps others understand and learn to ask questions (for example that can beget what is acceleration, force, or, yikes, mass?). The key is take it slow – give them time to digest, use examples and work through them explaining each step (don’t assume knowledge even basic stuff like roots and exponents), demonstrate relational things – how does v relate to a for example, and let/help them work through the equations so they aren’t just abstract.

It also helps if you can relate it to something they’re already interested in and understand. If they’re into astronomy, for example, start by showing them how to figure out basic orbits or calculate the approximate mass of a planet.

Oh and don’t forget that physics uses technical definitions of some common words which can trip people up for example “work (W)” make sure they understand how the terms are being used.

Your use of the words “very friendly” invites speculation that there is more than just tutoring on yours, hers or both your minds. I don’t recall tutoring in school involving “very friendly”!