There is some good info on introducing solids on the Raising Children website.

As a general rule, introduce on new thing at a time, give a small portion and watch for a reaction. If your baby tolerates it ok (no rashes, redness around mouth, diahorrea, etc) then it's ok. I chose to use foods that were lower in natural food chemicals - like pear, mango, pumpkin, etc - and waited until she was a bit older to introduce things with strong flavours like berries.