Generally I've been trying to follow Hungarian Notation where the prefix to the variable name tells you what kind of variable it is.
Points - pt: ptA, ptOrigin, ptScale
Objects - o: oLine, oMatrix, oArc, oText for various elements
Dimensions - w, h, or l: wBarrier for "width of Barrier", hBarrier for height, lEndPost for length. All of these are doubles.
Stationing - sta: similar to dimensions, but stations represent distance along a centerline, e.g. staAhead, staBack. Also a double.
Strings - str: strText, strCell for some text string that is to be turned into a text element or the name of a cell respectively.
Labels - lbl: lblLVC2
Text Boxes - txt: txtLVC2
Combo Boxes - cbo: cboScale
Button - cmd: cmdDraw
Form - frm: frmMain