The effective strategies for looking up words in the dictionary when reading are option 2 and 3.
Underline words then look them up when you have finished the book.
Make a list of words and definitions as you learn them.
When reading a book a person may find numerous new uknown words which should be looked up in the dictionary to grasp the message of the text. A good method is to underline all the new words we do not know. And after that, to create a glossary with all those new words in order to learn them and be able to adopt and use them later.