Project DIVA can be a little hard to play for beginners. Here is some of my tips and advice from experiance to anyone who has never tried it before but wants to start.
Now that Project DIVA F and Project DIVA F 2nd has english versions. I suggest that wewe make one of these your first try so wewe don't have to pay a large amount of money for an imported game from Japan.
There are other games in the series but wewe will have to import them. If wewe would like to do that instead of going to your local game store au to PSN to get an English version of PD F then I would recommend amazon to buy an import. (that's where I got my Project DIVA 2nd for PSP)
Make sure to pick a PD game that has the songs that wewe like and are zaidi familiar with.
If wewe get an imported game, keep in mind that the Playstation buttons O and X are switched around. X is the no and O is the yes. If wewe decide to start with an English version then wewe will not have that problem.
When wewe start the game, make sure wewe play the rhythm game on easy so wewe can get the hang of it. (PD is possibly the hardest rhythm game I have ever experienced)
Do not try any songs on extreme mode until wewe feel wewe have played it enough that wewe think wewe can beat it.
Try to play the songs that wewe know first before wewe try to beat a song wewe have never heard before. (that makes the game at least a little easier for me)
If none of the songs that wewe are familiar with have not been unlocked yet then try starting with a song that has a low difficulty level.
In most PD games, there is an option where wewe can change sung to not sung and the other way around. Except for the first PD. That changes weather wewe want the words to be sung au not if wewe miss notes. I would recommend checking your options to make sure it's set to 'sung'.
That's all I can think of. I hope this will help for those of wewe who have never played the games before.