modeling a nose and mouth onto an existing figure

Hi guys

Iv modelled a base figure with the help of background images, I have added eyes which went well but now I’m struggling on adding a mouth with lips and nose, I looked for tutorials but all of them are either modelling a nose and mouth while box modelling the face or sculpting the mouth and nose which I have no experience in.

Can anyone help

if you want to go the vertex by vertex way, select the central vertex just above the bridge of where the nose will be, go into side view, and extrude a profile, trying to match your number of vertexes with the next edge loop over. now go into front view, duplicate the vertex from where you started the nose profile, and shift it outwards a little. then go back to side view, and pull it in toward the rest of the face a little. now extrude your next row, somewhat following the contour of your first row. when you get to the end of the nose, bridge the two edge loops. do another one or two, and then do a little tweaking, and shift things into place. when you’re making less uniform contours, don’t be afraid to escape from the standard views. sometimes you have to go into another view, and do a little guessing, then go back and adjust things. try to flow with the natural contours of your object in your edge loops.
(edit) when tweaking, alt-S ( scale along normal ) can be very useful.