It's a good idea to wind down towards the end of each day with the same comforting ritual: putting away the toys, having a meal, running a bath. A soak in warm water can be very relaxing for your baby.
Once your baby is freshened up with a clean nappy on and in their nightclothes, choose a quiet activity, such as looking at a familiar book while having a cuddle, or just having a last breastfeed. Every mother has her own way of soothing her baby. Perhaps you could let your baby hold a special teddy or cloth while you sing a few lullabies.
A soothing going-to-bed routine can be very comforting for a baby. He or she will learn that the mood will change from 'activity' to 'rest', from stimulation to relaxation towards the end of the day. If your routine follows the same pattern every day, your baby will even look forward to this special time of being cosseted before the separation of sleep - and you will look forward to your evening off!
Certainly your baby needs to feel secure before they can sleep. But their security comes in part from your loving, relaxed predictability - not just from your presence. You don't have to be there when they go to sleep. Even when you're not actually with your baby, they can still sense your presence.