G'day MrsOrlandoBloom,
It's really up to you. I don't know if you have a better chance by sending your own photos but if the Celebrity has run out of their own, then yes it definitely helps!! Plus, if you send your own and the Celebrity is able to sign them, it is kinda nice having a different signed photo that you chose (and therefore really like) of the celeb.
Basically it's up to you but a lot of the time, I include photos for the Celebrity to sign because they're my favourite photograph of the particular person or it's a photo from a movie that the person was in.

I've had quite a few fantastic successes sending my own photos. {love}
Novan wrote:No because I have sending picture to Johnny Depp and when I received it the where alll autopen.
Unfortunately, Novan, Mr Depp only sends Auto Penned photos.

Sometime they will autopen a photo you send with his signature but mostly they just send you Mr Depp's own photo.
It's a good idea to check the previous feedback of the people you are planning on writing to. That way you will be able to see if they have signed other people's photographs in the past and are likely to do the same for you. There's no certainty in this hobby but you can do your research and hope for the best!

Madame_Malfoy