Songwriting - Coming Up With a Song Progression for Your Song
If you haven't already seen it, do a Google or YouTube search for "Axis of Awesome - 4 Chords." They're a group that put together a video that strings together a ton of hit songs that use the I-V-VIm-IV chord progression. It's really incredible when you see just how common that chord progression is. You've heard all these songs, but you probably never realized they have the same chord structure when you're listening to them. So make sure you check that out if you haven't already seen it.
With that in mind, when you're looking at other songs to see what chord progressions they use, it's a good idea to modify the way they play those chords to give the chords your own style. Here are three ways to do that:
One thing you could do is to change the length of how long each chord is played, by either shortening or lengthening each chord. You could even lengthen some and shorten others. You'd still be using the same chords from a song you referenced, but now they'd have a totally different feel.
Another modification you could make is to use the chords from one song that you like but use the rhythmic feel and strumming pattern from a second song you like. This will really breathe a new life into those chords. So maybe you'll take the chords from "Back in Black" by AC/DC, but you'll play them with a fingerpicking style and rhythm similar to what's used in "Blackbird" by the Beatles. When you start thinking in this way, you can come up with some really interesting collisions that may work great for a song of you own. You'll have to experiment with it to see what works best.
One other thing you can try is taking the chords from a song you like and playing twice (or half) the amount of notes on each chord, while playing the overall chord the for the same amount of time as your reference song. This is another way to mess around with changing the rhythm of the chords, except now you're not relying on a second reference song to do that.
Experiment with these ideas. You just might love what you find!