One tube is usually sufficient to caulk around two doors or windows. Six should be enough to start the job, and you can always buy more tubes as you need them. Do not apply caulk in cold weather. The minimum temperature for good adhesion is usually around 40 F, so it s best not to put off the job until winter. The caulk manufacturers directions will also have specific temperature recommendations for using their products.
Low humidity is also important, so the cracks aren t swollen shut with moisture.
Make sure the area you are working on is clean and dry. Remove all built-up paint, dirt and old caulk with your screwdriver or putty knife before applying any new caulk. Larger cracks and seams will require filler material before adding the caulk. Start in an inconspicuous location and have a rag ready to clean up mistakes. When applying the caulk, hold the gun at a 45 angle.