As far as what to do, the advice you have been given so far is great. My tiel moved at a rapid pace in terms of wanting to be with me when I brought her home, but all tiels are different. Some like to go at a slower speed in terms of interaction and bonding, and that's okay too. Respecting that will give you the best bond with your birds, because they will trust you not to push them too far.
Treats are always a good way to go when you want to help get them used to your hands and presence. Millet is a sure way to a tiel's heart. Drop a treat nearby every time you walk past their cage/s. If you have them out of the cage, you can drop a treat close to them. Once they start becoming more comfortable around you, you can try feeding treats by hand.
Also, I would highly recommend working on target training with them to get them where they need to be, and also for bonding purposes. It's very useful when you need to get them back into their cage when they're not used to you.