First and foremost, it is important that the surface to be painted has been properly prepared. Scrape off any loose paint and primer and apply fresh primer to any exposed wood sections. Also check the window putty: maybe you have to remove it and apply some new? Use Titan window paint, our specially formulated product for windows and woodwork. Those surfaces usually use planed and sanded wood, so a different paint structure is required. Do not forget to use a good quality brush for this kind of work, it really makes a difference!