Analyse where you are today
Look at your Google Analytics (or other webstats) to see:
- How many unique visitors your site already gets
- What keywords they search to find you
- Which page they initially land on
- How long they stay
- Which is the last page they look at
Even more importantly, establish how many enquiries, leads, sales, newsletter signups etc. you get from your current site.
This sets a benchmark that you can compare against when you launch your new site (be sure to measure using the same tools so you are comparing like with like).