Very first foods should be easy to digest and unlikely to provoke an allergic reaction:--

FIRST FRUITS: Apple, pear, banana papaya and avocado.
Banana and papaya do not require cooking provided they are ripe and can be pureed or mashed on their own or together with a little breast or formula milk. Bananas are not suitable for freezing.

FIRST VEGETABLES: Carrot, potato, swede, parsnip, pumpkin, butternut squash and sweet potato.
I find that root vegetables like carrots, sweet potato, parsnip and swede tend to be the most popular with very young babies due to their naturally sweet flavour and smooth texture once pureed. Butternut squash also makes good baby food in the first few weeks. The best first fruits for young babies are apples, pears, banana and papaya and it’s important that you choose fruits that are ripe and have a good flavour, so it’s a good idea to taste them yourself before giving them to your baby.

BABY RICE
Another good first food is Baby Rice. Mixed with water, breast or formula milk, it’s easily digested and its milky taste makes an easy transition to solids. Choose one that is sugar free and enriched with vitamins and iron. Baby rice combines well with both fruit and vegetable purees.

It may be a good idea to begin with to give your baby a little milk first before his solids as he may be more receptive to this new way of eating if he is not frantically hungry.

Recently the advice was to introduce each new food separately with a space of three days before introducing another food, however unless there is a history of allergy or you are concerned about your baby’s reactions to a certain food, there is no reason why new foods should not be introduced on consecutive days, provided you keep to the list of Best First Foods.