If you have already whisked all of your ingredients together, and you notice that there are some lumps in your batter, you can try to get them out by continuing to mix. But often that method is repetitive and not very effective. A way I have found to work is to use a small wire hand strainer. Pour the batter through the strainer into another bowl. Using the back of a spoon, try to push the clumps through the strainer to help them disperse! Either way, ensure there are no clumps of flour in the batter. It is important that the batter is completely smooth so the crepes can cook properly.