Learn as many spellings as you can from the Y3/4 and Y5/6 statutory word list. Use the grid to pick different activities to help you with your spelling. Choose between 8 and 10 to learn each day. Some of the words are really tricky so you might choose them again until you know them off by heart.
Why not ask a family member to test you on your spellings once you think you know them.
You can also go on to Spelling Frame to learn and play spelling games.