You can try to play the previous games or if you only want to know about the Metroid Universe you can go here:

http://www.metroid-database.com

Even they have the official manga so you can learn about Samus past

I used Metroid Recon to fill me in when I jumped into the Metroid series.

http://metroid.retropixel.net/

I've only beaten Metroid, Metroid Prime Pinball, and Super Metroid, in that order. I've played a little bit of Metroid II, Prime 1, and Prime 3.

Now I'm super-pumped for Other M so I just started the whole Trilogy on the Wii this week. It's really awesome and I can't believe I took this long to play it.

If you only have time for one game, download Super Metroid for $8. Other M starts with the ending of Super Metroid. Playing through that ending will really help you get pumped for the beginning of Other M. Otherwise, don't play any of them or read any spoilers. I'm sure the game will be able to tell its own story and exist on its own.

NOOO! you ruined marley & me for me!!!!! actually it was playing on the plane when i went to italy this summer, i fell asleep...i think... it was that boring, i wasn't sure whether i was sleeping or not.

anyway, first off do yourself a favor and go play the old metroids (SUPER METROID) and metroid prime imo. that game so awesome. part 2, meh you can skip and read about it and as for part 3 (right guys? part 3 came out, corruption. I hope im not makign a fool of myself) I never played it so i can't tell you bout this lil bugger

I'd go back and play them all. With the delay, there's plenty of time.

If you had to play only one, it would have to be Super Metroid. Not only is it the pinnacle of the series, but Other M picks up where it left off and has a lot of ties to it (and Fusion, but Super moreso).

so if you have a thing against playing retro games (some people do) you can always try shadow complex on the XBLA, it's a complete rippoff of the classical metroid formula (with HD graphics and voice acting... it's still inferior though but great game none the less).
And yes Super Metroid is the best one.

Another M though seems like it'll be a bit different from the standard formula but still great.

Hunters was after Prime 2, i thought...

Samus is a chick!

That's not a problem. I thought you were going to say you were dating Mother Brain or something. Gametrailers should have a video showing the complete history of Metroid. I'll see if I can find it for you.

In the meantime, download Super Metroid from the Wii Virtual Console. It will give you a pretty good review of what you need to know AND it's a kick ass game.

I was initially undecided if I should buy Metroid Prime Trilogy, but I did buy the game and I was mesmerized by the quality of the three games. If you like FPS or FPA, enjoy games with tranquil enviroment, and like a game with a fresh storyline then buy a Metroid game (in this case buy Metroid: Other M).