Bridesmaid dress alterations, please any help is appreciated?

the dress is too long and it is an empire bodice ending just under the with 2 straps, the bodice has to be also lengthend as they dont fit into it, it has a seam at top of shoulder, do i shorten the dress 10 inches and add bits of it to the top of the bodice strap? and then just rehem it. is there any tricks i should know? i dont have money to get it altered professionally.