The shingles seen here were installed too close together and lack proper spacing - they expand when wet
Let the wood acclimate at the building site for a few days before installation.
Use high-quality materials.
Use the proper sheathing / moisture barrier under the shingles.
Use proper spacing between materials (check manufacturer guidelines).
Use the proper fasteners.
Click here for more details regarding installation.
Make sure any contractors working on your house are licensed and insured. Obtain three or more estimates for each job.Check references.