Do you remember the hours you spent memorising words like ferry, pencil sharpener and horse? How many times did you ever actually use these words? Some words give you a far better return on investment than others. I remember learning French at school when I was younger; we spent hours of valuable class time learning useless vocabulary for kitchen utensils, extended family members, clothing and rooms in a house. This was all good and well except when I went to France and got lost in a street market, I had no idea what to say. Start with the 100 most common words, learn them and make sentences with them over and over again. Learn just enough grammar to be able to do this and do it until you feel pretty comfortable with all of them. Then start expanding your vocabulary based on what is useful for you.