I swear by the Body By Victoria bras. They are super comfy and don't show through tees. They are pretty plain looking though. There is a super cute Angels Ipex bra that is smooth enough to wear under tees but it runs small and I'm a D cup so it didn't work for me.
I agree with everyone- get measured and let the sales women do their thing. They're usually really good with making suggestions.
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"If you have men who will exclude any of God’s creatures from the shelter of compassion and pity, you will have men who will deal likewise with their fellow men." — St. Francis of Assisi, 1181-1226