"can I include my parents' salary, since they are in my household? "
If your parents plan on helping to pay for the credit card, I would say yes...
Deep down it aint gonna matter too much. Credit card companies typically pay more attention to how many people you screwed in the past, versus how many positive things you have ever paid off. You could put a million dollars down, but if you screwed every single one, you are not getting anything from then.
Also, I have heard how bloating this number actually hurts your image, since if they look at your history(assuming you have any) and you missed payments, and such, but make tons of money, they will see that as you not caring to pay for what you owe. BUT, if you made paltry money, yet only missed like a payment or two. They will get the idea that you make good on your promises. It also comes down to how badly they need new customers, and how low they have lowered the requirements for their credit lines... Good luck....