Most people’s instinct is to pull the caulking gun when trying to fill a joint. Next time, try pushing the gun instead. You’ll get a more even application of sealant and a better result. If you want a nice straight line, take the time to use masking tape, such as Scotch Blue, on both sides of the crack. Big hint here: putting tape on freshly applied paint to mask for caulking or painting a second color will only result in the bottom layer peeling off. With latex paint I wait at least a week or more before putting on tape. Some of the “low adhesion” tapes will work, but I find patience works better.
One of the more common mistakes made when caulking is trying to caulk a gap that’s too wide or deep. If the gap is more than 3/8-1/2” push in a closed cell foam backer rod or try to caulk in two passes. When the caulk touches 3 sides or more, such as two sides and the bottom, it will tear away when the edges move. Again you can install a backer rod or use a bond breaking tape on the bottom of the “crack”.
We like to recommend using a caulk/silicone sealant, such as Alex Plus, which is easy to use and cleans up with water. For connections between wood, metal and brick we have been having great success with OSI’s Quad Max. Both come in multiple colors.