You always want to have at least 8 different clients and the ideal is usually 10-15 since once you get over 20, it can be hard to balance everything. You always want to be able to give great service without focusing completely on one or two clients.
If you do find yourself with only one or two clients, you need to evaluate their uniqueness. Could you take what you're doing for them and do the same things for a similar client? Do you already know of some prospects whose needs would be similar? Diversify your clients, but if you can, keep clients with similar needs to make your workload just a little easier.
To learn more about diversifying your client list and providing exceptional service, read the full article (link above).
Added by Computer Consulting 101 Professional Kit