State the method you used to study this problem. Be brief, more detailed description will follow later. State the principle results of the investigation. State the final conclusion suggested by the results. The last point is the one most left out of introductions.
Many people make the mistake of keeping the reader in suspense.
This may make great literature but poor science. The greatest invention of the nineteenth century was the invention of the method of invention. Most of this section should be written in past tense. The detail of the equipment used and each step of the procedure is extremely important. This is where good notes in your journal will be very helpful.