Send a list of the records you put in the package.
Send a copy of your copy the records.
Summarize the facts in the case; help your expert get up to speed quickly.
Consider asking your expert specific questions you need answered. "Did cutting the bile duct fall below the standard of care?" "Was Mrs. A adequately informed of the risks of the surgery?"
Send everything your expert needs to formulate a rock solid opinion. Don't pay to have a surgery-gone-bad reviewed until you can send the operative-report. If you're unsure what to include, pick up the phone and ask the expert.
If your client's version of the facts differs materially from the chart's, be sure the reviewing doctor knows your client's version of the facts.
Separate, tab and label the different sections of the chart!!
One big section, with subtabs, for each hospital admission, one for each doctor's office. Put everything in three-ring binders.
 Read the autopsy yourself. Don't sink thousands of dollars in a wrongful-death-by-heart-attack case only to have your expert point out that page one of the autopsy report also shows widely metastatic cancer and a six month expected survival. It happens.
 Beware unreadable photocopies. Your expert won't know about a critical CT scan if his copy of the report is a black smudge.
 Beat back your urge to date order the chart as a whole. Date order is how you've been trained to think. It is not how doctors think -- don't confuse your expert!