There's good advice here already. You must definitely apply the
80/20 rule. Buy Richard Koch's definitive book on the subject. There's even a 5/50 rule that 50% of your income comes from 5% of your customer base. These are your raving fans who buy everything that you offer. Focus on them first. Look after your other remaining clients after that and leave the new customer generation until last.
Use outsourcing if you can. It does take some extra effort in the beginning and you do have to go through a learning curve to assess people and instruct them properly. The book 'The Four Hour Work Week' gives a good introduction to finding and using outsourcing.