It's okay to start with easier sudoku at first! Soon you will understand the basics and you will crave for harder sudokus to print.
You may also find it useful to write down the possible digits for each square in their respective corners. This list of possibilities will get shorter as you progress in the puzzle and you will solve it in no time!
Don't get discouraged. Sometimes taking a break and coming back with fresh eyes can help move past what was blocking you.
Start with the rows with the less blanks. Then to the squares with the less blanks and so on.
Sudoku is not a guessing game. If you feel like you have to guess the answer, stop and go to another blank.