The general guideline / rule for lettering thickness is that as the lettering gets smaller, the line thickness gets thinner. Drawing titles and subtitles are underlined but the underlining should not touch the lettering. Lettering larger than ¼ “should not be standard hand lettering, but should be done by outlining typeset letters by hand with a thick line. Drawing titles at ¼ “ with a thick line, subtitles at 3/16 “ with a medium line, general notes at 1/8 “ with a thin line and miscellaneous notes at 3/32 “ with a very thin line