hi sabrina_diamond! firstly, always nice to see some new artists around here!
as you didnt say not to post con-crit, here it comes!
first things first, Lisa has an incorrect number of spikes on her head - she should always have 8. her nose is slightily too large and her overbite also is too big. strangely, Lisa has no ear... mabye vampires dont have ears, i dont know as i am not a vampire enthusiast, but i can guess Lisa does need her ears! lol

Lisa also does not have a neck.
Her torso looks fine to me as far as proportion goes. Her arm is a little odd though, and possibly a little too long.
Mark (i assume here that the man on the right in Mark?) has an incredibly huge ear that takes up a fair amount of his face!
Apart from the proportion things, the lines are fairly messy, but that is alright seeing as this is indeed a sketch! on another note, there is not much to link the scene with a restaurant. mabye you could include a backdrop of a few chairs and tables, which would add another level of interest to the picture.

i must say though, i adore Lisa's eyes and eyelashes. they are very well done

to conclude, this is an interesting and welldrawn picture, with some room to improve. but then, we aren't ever perfect

looking forward to seeing some more drawing from you very soon

keep it up!