请教给位外贸老前辈，我该如何更有效地回复客户的询盘

we are interested to established and open long term business relationship with your company,
also, interested to appoint your company as our sourcing/purchasing exporter for any of our requirements products in your country.

we are serious to purchase below items continuously, please quote the below item in u.s.dollars for our market negotiation and to enable us confirm to you our first order with advance payment before shipment.

payment terms: by 30% advance payment before shipment

we looking forward for your reply.
请教给位外贸老前辈，我该如何更有效地回复这位客户呢