Hi, I'm a newbie to this forum as well. I have a baby sun conure that is 29 days today. I have experience with birds and was a vet tech for many years. BUT raising a baby bird is HARD!! Your entire day and night has to be planned around the feeding and care of your baby.
The biggest risk is with the hand feeding. There are several important factors:
1. Temperature- needs to be 104-106 degrees. If too hot you can cause severe crop burn and too cold can cause a slow digestion or the baby won't eat.
2. Method- aspiration is a HUGE risk if you don't know what your doing. The only way to learn to avoid this, is in person, with a knowledgable hand feeder.
3. Amount- too much can cause strain on the crop. The crop needs to empty properly at least every 24 hours, some say between every feeding. But you don't want it empty for too long or the baby can start to lose weight and nutrients.
4. Type of forumla and consistancy- a high quality bird hand feeding formula and it need to be prepared properly and the thickness should be dictated on the birds age. Again too thick it could set up in the crop and not drain properly and too thin, the baby doesn't get the nutrients they need.
Of course a 3 week old baby can't maintain their body heat, so you have to provide the heat for them. Experienced breeders use brooders, some use heat pad or light bulbs. At 3 weeks they need to be at 81-85 degrees.
I know I haven't touched on everything. There is so much I have learned over the years and I still feel like I am not an "experienced" hand raiser. So my advice is to allow the breeder to raise this baby and you adopt when the baby is completely weaned and ready to start a wonderful life with you!