Lips must be hydrated and exfoliated, so I recommend using the Sara Happ Lip Scrub (more details here) first then popping on some Lucas Pawpaw ointment while you do the rest of your makeup.
Blot off the remaining Pawpaw ointment off with a tissue, then apply a lip primer such as the Kiko Lip Base (£5.90 here). The primer neutralises the colour of your lips so you can draw your lip line in where ever you want it to be. The neutral base also helps to make your lipstick colour pop.
I have fairly full lips so I draw my natural lip line in using the Kiko Invisible Lip Liner (also £5.90 here). This is a waterproof clear pencil that provides a barrier so that the lipstick doesn't bleed.