Yellow letters - Lined or Unlined paper?

[Teresa DelaMater]

Hi y'all! I'm getting ready to send out my first direct mail marketing letters, and I was wondering if I should buy lined or unlined paper. I'm actually having a tough time finding lined yellow paper 8.5x11 that is thick enough not to jam a printer, so I'm leaning towards the unlined paper which is easier to find. Maybe I'm overthinking this, but I'd appreciate some advice! Also, what have people written on the letter that has generated the most leads? Thanks!