Start with homemade veggies, all the orange and yellow-flesh veggies is great to start with because it's naturally sweet (pumpkin, butternut, carrots, sweet potato). Start with one type, butternut, first. Stick with this for 2 to 3 days before you introduce the next one. Don't add any sugar or salt or anything else, if you want to thin it a bit you can add a tiny bit of water or formula/breast milk.
We started cereal about 2 weeks later than veg, we also started with Hipp but changed to Cerelac within days because she didn't seem to like the taste of Hipp.
Remember that the process is likely to be very messy, your baby doesn't know what a spoon is, never mind what to do with one! Just persevere, baby will get the idea eventually. At the beginning 2 or 3 teaspoons will be enough, continue with this until baby knows what to do.
Lastly, always introduce new food in the morning or during the day, never at suppertime. This is just to make sure there is no allergy or baby doesn't have cramps etc.