Realize that breakfast and dinner will be smaller meals, but that at midday the meal
will be large.
Siesta is real and you will learn to love it.
Spaniards are often late and it is not considered rude. Also, do not expect quick
service as the lifestyle is more "laid back".
If you are not used to walking, get used to it. Sometimes public transportation is
not the best way to explore.
Go to museums and other cultural events even if you do not do much of that right now.
You will regret it if you do not.
Spaniards, like many other Europeans, wear clothes that fit closer to their bodies.
They also have fewer, but nicer, outfits (because good quality clothes can be pretty
expensive). They will notice baggy clothes and probably comment on them.
Be prepared for besos - in some situations, everyone is going to be kissing everyone
(a kiss on each cheek) and you are going to have to get used to this. Even when you
first meet people who are friends of a friend, they will give you besos. Just remember
to offer the right cheek first.
Be aware that the distance between people who are just standing and talking is close
and may make you feel uncomfortable at the outset. Do not feel invaded! This is just
the Spanish idea of personal space. You will get used to it and not even notice it
after a short time. Buses will often be crowded and lack of personal space is a given.