Well I dont know exactly what you want to sound like but the best advice is to practice (if that doesnt seem obvious xD)
You may also want to try drinking a LOT of icewater. Helps. Not just that day but drink a few glasses of truly frigid water a day until then. Then stop that day o.o Swallow immediately, dont let it stay n your mouth long.
Get a good idea of what you want to sound like... Yeah that's about all I've got. Now I'm not exactly a perfessional vocalist but I'm not terrible. I hope my advice has helped... In some way o.o