Simple.
* SEPA payments, for an acceptable price (1-2 euro per transfer) and a SEPA account to pay to. Yes, you may need client disclosure - guess what,I dont care. My bank knows who I am, my brokers know who I am and the real exchanges I am involved with know exactly who I am. No reason not to sign an agreement with you and provide you with copies of my papers and the registration of my business.
* Better trading interface. They ALL suck, yours is no difference so far. Seriously, Give me something a free of cahrge real broker interface has. If you dont kno what that is, open a dummy account with a broker to see waht a decent trade interface looks like
* Miners possibly would love some automation for larger odrders. VWAP based selling and purchase algos wuold be interesting, so you don't kill the market with one large oder. If you dont know waht VWAP is, talk to someone with real trading experience
* Full disclosure, every month. I mean YOUR balance sheet. How much moeny you have on waht accounts, how much liability you have towards customers. I wont trust ANY brkoe that does not give me safety - as you are unregluated (contrary to any non-btc exchange) the minimum I want is to see you are fniancially sound. Audited.