I don't usually use a lipbrush with lipstick; I just apply straight from the tube. I tend to only use brushes with pot glosses or l'oreal colorjuice, which i find apply awkwadly straight from the tube. But I will have to try applying straight and then using the brush to distribute evenly. A good idea!
for lighter, more neutral shades- I apply straight from the tube, but if it is a darker color, i.e. Dubonnet, ,Fresh Morroccan, etc.. I use a brush so I dont end up looking like a four year old did my lipstick