Help baby starting solids

Sammy

I am a first time mother my baby just turned four months. We talked to his paediatrician today he gave us the OK to start solids. He told me to first start with cereal then proceed to fruits and veggies. i’m just wondering how often do you give him cereal a day and when? Usually before or after a breast-feeding session? Can I mix the cereal with breastmilk or does it have to be water? Any tips I should know of?