Help with design

I have a database which I have constructed which has many tables. It needs
redesigning as I don’t think it’s an effective database design, as when
trying to achieve tasks its always giving me trouble. The db was originally
designed with jus 9 tables. I now have to make amendments to accommodate
expansion.

What I am trying to get the system to do.

The db holds a list of customers. The customers can enter the system via an
agent, or via the client making an appointment with a client. Whether the
customer enters the system via an agent or via the client, I need to record
all the meters details, and renewal dates. I then need to keep a status of
the new clients which are coming into the system. When a new client has been
successful, I will update the system to allow the full meter details to be
entered into the system.

The flow of the system is as follows.

Customer into system (agent = non appointment, client = appointment)
Record all preliminary meter details
Keep a status of all the clients.
If successful with client record all meter details. Also allow to record
special meter details.

An employee can enter any customer into system and also make appointments,
for customers. They can also enter agents and agent personnel into the
system.

I was wandering if someone could help point out weakness in design if I
emailed it, or point me to a somewhere with good design solutions. Any help
on a more efficient design would be appreciated. I do know I have to change
the customer table, to accommodate many address.

Thanks

Ronnie