Poor gramar and speling looks like a fourth grade education. Don't tell your life story in the ad. Leave them asking for more. Do tell the important points in your ad. If you have a sense of humor, give the reader a chuckle.
Online personals is a sorting business.
Don't feel you have to write back to every response you get, and don't take it personal if you don't get a response to an ad you wrote to youself. To get down to the eligible ones, remember the answers to those questions above - what's important to your needs. Often we must go with our gutt when someone says something stand-offish, inappropriate or extremely vague. Once you determine a response has intriqued you, it requires a bit more narrowing down if you're looking for someone special for a serious relationship. Some responses will be short, and need another email go around to determine if they stay in the maybe pile or hit the recycle bin.