If you're using a getPage call to display the products use a standard &sortby=`whatever` (can use JSON strings here) or if you're using a direct call to the msProducts snippet use the format [[!msProducts?sortby=`msProduct.pagetitle`]] or [[!msProducts?sortby=`Data.price`]] or to display items marked as favorites [[!msProducts?where=`{"Data.favorite":"1"}`]]
Sorting by TVs can be achieved through such things as:
[[!msProducts?
&includeTVs=`action,discount`
&sortby=`TVaction.value`
&where=`{"TVdiscount":"1"}`
]]
More examples are at:
http://bezumkin.ru/modx/minishop2/snippets/917/ (Russian page)