Be Prepared for Touch Ups and Repaints
At some point you will most likely want to touch up a paint job, or you will have some home improvement work done, but want to keep the color that you currently have on the walls and trim. The best way to ensure that you will be able to match the colors is to keep a record of the colors that you used.
The easiest way to do this is to keep the old paint. But, if you do this there are some actions that you must take to ensure that the paint is usable. First, make sure the cover is tight. This means that all of the paint on the rim should be cleaned off before you put the cover back on. You can buy spouts that are fairly inexpensive that attached to the rim that makes pouring the paint easier and keeps the rim clean. The purpose of keeping the rim clean is to allow for a tighter seal when you close the lid. Second. store the paint in an area where it will not freeze. If paint freezes it might ruin. This is especially true for water based paints. Third, keep a record of the color. Usually, paint stores will put a sticker on the lid, with the color name, date that it was mixed, and the pigment amounts used. If they do not do this, ask them to write it on the lid. But, you must keep the top of the lid clean. If you use all of the paint, keep the lid, or write down the information and keep it in a place that you will be able to find it later--don't be like me and keep it in a pile on top of your bureau.
If you take these steps you will be prepared when it is time to do some touch up work, or paint a new patch of dry wall after your home improvement work is complete.