Do your filing
In addition to your client files, have files for everything related to running your business. Then, set aside time each week to file everything you have dealt with that week. I use the last half-hour on a Friday for this.
Have checklists for every process in your business. For example, when you take on a new client, have a checklist which prompts you to check that: you have received the signed contract, you have sent your Welcome Pack, you have set up an appropriate email address, and you have their stationery. This saves time and prevents things being forgotten.
Check and update your website
Check that your website is up-to-date and current. Set aside time, perhaps once a month, to check all the information is current, and add anything new that your clients and prospects might find useful.