I also used 3 different sized photos. I made sure that each layer overlapped and provided continuity throughout the layout. To bring everything together I used the large Melissa Frances frame for my title. This frame overlaps the photo at the bottom left as well as some of the layers on the right.
Because the top left corner was so bare to me I decided to stamp a mini border to balance the layout out. With the stamp alone I didn't like it - and was upset that Ididn't just leave it be - but I added a neutral tag to take away some of the harsh black.
I guess that wasn't one tip that was a few - heee - I hope it made sense and provided you with some background on how I put the layout together.
I hope you have a wonderful weekend!