Wearing well-tailored clothes will also improve your work!
「仕立ての良い服を着ていると、仕事もはかどります!」は英語で「Wearing well-tailored clothes will also improve your work!」という意味が良いと思います。
仕立てーTailoring
良いーGood・Excellent
服ーClothing
着るーTo wear
仕事ーWork
はかどるーTo advance・To make progress
「自信が持てるようになり」には「You will feel more confident」や「You will be confident」という表現がよろしいです。
Wearing clothes that are well made at work will help you get through your work better.
この場合、次のような言い方ができますよ。
ーWearing clothes that are well made at work will help you get through your work better.
「仕事で仕立ての良い服を着ていると、仕事が捗る」
clothes that are well made「仕立ての良い服」
to get through one's work better「仕事がはかどる」
ご参考まで!