As your body accounts for up to 80% of the drag on the bike below are some good ways of getting more aerodynamic. It is always a good idea to be able to quantify these improvements but if you are without the proper resources for doing so just try it out and see how they work:

• Bring your elbows in on the aerobars so they are a little bit narrower then your hips. This will help create a smooth flow of air down the sides of your body. Be careful not to go to narrow and inhibit your breathing by squeezing your chest together.
• Get an aerohelmet. Yes the funny looking ones with a point. They don’t look good on anyone unless you racing. BZ faves are the Rudy Project Syton and the Spiuk Kronos.
• Check your bike and see if there is a 5-10 centimeter difference between the height of your seat and the aerobars. Now 5-10 cm is a big window but for most people this will allow for a good range to get low and aero! When dropping the height of the handlebars be conservative by going down 2-3 millimeters at a time.
• Keep your clothing tight and reduce the number of seams and zippers. Every little bit helps