Now that your trim has been installed around your house you need to go through and seal up every place where water could potentially get in. You need to seal the seams between your trim pieces, also in the corners you want to make sure you seal up every gap. You want to make sure you use an exterior sealant. You will want to try and choose a sealant that is close to the color of your home, this will help limit the amount of touch up paining you will need to do. Also if you cut the tip of your sealant at a 45 degree angle it really helps when you go to apply it. to insure a good seal you will want to put a little bit of sealant in the seams and then run your finger down to smooth it in.