The probably first thing I noticed in Estonia, were the different eating habits:
Growing up I was always told to wait until everyone at the table has food on their plate and only then I can start to eat. While this is a “rule” that applies to (probably) everywhere in Germany, in Estonia it depends on the family and is in my (host)family only used with more formal guests.
In Germany it is quite common to eat with knife in fork, even when you could also eat only using a fork (e.g. pasta, salad). Here (in Estonia) we only knives to eat, when needed. Again: this only applies to the everyday life meals and not when we have guests.
Some notes to the food as well: Due to its boreal climate traditionally there is not in every time of the year fresh food to be had. The traditional Estonian dishes include therefore ingredients that are non-perishable such as gherkins, potatoes and meat.
I live with my (host)family in the country side of Estonia and I think there are some habits and customs connected to that as well:
Our door is almost never locked. Only when all family members leave the house for a longer time and at night the door is locked.
People come and go whenever they want, normally without prior notice. If they do, then just a few minutes in advance. We have quite often people – usually neighbours – at our place. At least just as often we go to the neighbours’ place (the ones who also have an exchange student). When people visit each other in Estonia the visitors always bring something along, usually food, sometimes also flowers or other useful things.
It is also normal to go to sauna in Estonia. Ours is not completed yet, so we use the neighbours’ sauna. For that I already go to their place thrice a week. When it was colder we also made snow angels and went into an ice hole in the pond. When the ice melts we will just bath in the water.