I am not a professional steam trader but I like to trade items from time to time.
Trade Rules:
1. I am always nice and polite, act same please
2. Item prices always change. so both items having same price is not red line for me. but don't bother sending trade offer that item prices are highly different.
3. I never promise anything outside of valve specified trade system ( steam fund, real money or etc ) and I don't accept it either.
4. it's not my obligation but if you are dissatisfied with a trade that you did recently, feel free to talk about it with me. based on how fast you act and the reason you are dissatisfied, we maybe can trade items like how it was in the first place.

remember that steam is not stock market and we all are here to enjoy games that we love.