Merging changes back into the trunk incorrectly can really screw things up. Trust me, I found out the hard way. Below is a checklist of steps to follow.
1. Update trunk from repository
2. merge branch from trunk and take care of any conflicts
3. View localhost and make sure everything looks good
4. Commit merge changes to branch repository
5. Merge branch into trunk locally. Perform a test run first, then merge.
6. Fix any conflicts
7. Commit to repository trunk
8. View development or staging server to verify changes
Below is the interface for TortoiseSVN and sample data for when you “merge two different trees”. Select the trunk in the first drop down and the branch in the second drop down. The result of the merge will be stored in the trunk. Remember to commit your changes afterward.