Many times this is not a solely self-aggrandizing enterprise. Writers are generally a helpful lot. This month's featured market is full of good advice for young writers, offered by the more experience with the sole aim of helping others. As you are now, so once was I, that sort of thing. However, there's something about good intentions and a certain famous road.
Experienced writers can give some great helpful tips.
Read the magazine before you submit. While that might be impractical all the time, the first story I sold was written with a specific market in mind, so I have to give my friend her due. The advice was sound, and the results speak for themselves. God, there are many. Never submit to a non-paying market.