negotiating by myself with credit card companies

hi guys i have 12,000 in debt with seven credit cards i am 2 months behind on all. and i am ready to start negoitiating i was just wondering about what percentage of my balance should i tell them i want to pay starting out i know people usually say 50% of my balance i was just wondering if i should ask them to wipe out more than that.i currentley dont own anything and at this time i really dont care about how my credit report looks. bassicaly i dont have anything for them to try to take fom me. but im trying to avoid bk because the lawyers cost so much and the process is just too much and am not guaranteed tht i will save anymore than negotiating myself. basically i just want a figure i should start out with percentage wise because i know they will most likely counter. any input would be greatly be appreciated thanks john