You can practice labeling components by clicking here. You will be presented with images representing independent component just like if you were actually submitting labels, but your answers will not be saved. Instead, when you submit your answer you will be presented with the answers others have given for comparison. This feedback can help you gauge your strengths and weaknesses as an IC labeler. Just keep in mind that everyone can make mistakes so often there will be disagreements in the labels you are shown. Even between experts.
Additionally, example component images are provided below. The link above presents components in a random order. The ones below will remain the same, in case you need examples to compare. Click on all the labels your feel are applicable and the color will change according to your answer as follows:
Marking "?" is ignored here as that category is user dependent.