Well the best advice I can tell you is to visit the CIA World Fact book website. Go to http://www.cia.gov/cia/publications/factbook/index.html. Find out how long you will be at your destination and dress according to the fact book. The last thing you would want to do is bring shorts and you are in a cold weather country like Estonia. A few suggestions.
Bring sweat and jogging suits. Most gyms in Europe are not heated so you will need to keep warm until your body warms up to the room.
Also bring one or two nice outfits but don't go all out because more than likely you are not going to wear them. Better safe than sorry. But be ready for rain or shine, hot or cold.Bring a pair of house shoes or sandals. You may not be accustomed to taking your shoes off every time you go in and out of your house in America. In Europe, the streets are not as clean and when you get home or to someone's house you do not want to track dirt all over the floor. It is like no shoes on your mama's white carpet. You will be upset if you bring all your good shoes because they will only get ruined. Bring a pair of I don't care shoes. These are for your walking to and from the destination. Normally, at home we match the outfit with the shoes well in Europe you won't have those shoes for that outfit so it is your choice. Honestly, you will not wear a lot of the clothes you pack because it is not worth the hassle of them getting dirty. In most places you will have a washer but may have to hang dry your clothes.