Be professional. Research agents and talent recruiters. Read the requirements and submission guidelines and follow through accordingly. Do not add extra things to grab attention, such as sending flowers or submitting a letter on pink paper. If you seem difficult to work with, they will not want to work with your baby, no matter how adorable he is.
Take your own photographs instead of spending money to get professional photographs of your baby. Until you are signed with an agent, do not bother with going the extra mile until requested. Most agencies do not require professional photographs for babies because they change so much within a few weeks.
Make sure you submit a variation of pictures. A good-looking baby is subjective. What agents look for is personality and facial expressions. The photographs should capture moments. When snapping pictures of your infant, think about what commercial your baby could be in with that photo.
Enter your infant in modeling contests. Find free competitions online that may land you money or a contract. Also, check out local clothing stores and see if they are looking for infant models. Do not bring your baby when you go to inquire. Bring two or three photographs to show if they seem interested and ask for pictures.