try your best. as i read on the peta site:
Looking for .001% animal ingredients on EVERY packet is insane, and it shows others who may be interested in going vegan that the veg lifestyle is very difficult to live by.
Your best bet is to research what you already have in your cupboard/fridge and see what is and isn't vegan, then start with the obviously vegan stuff (so good, for example) and slowly expand. I found my first two months of being vegetarian, I ate nothing but oriental noodles, because i didn't understand what was and wasn't vegetarian. And i'm going through that phase again, going vegan, except most of what i eat is tofu and potato

but, with time, I will learn what is vegan, and i'll buy it. It is dificult at the start. If you're not already veg, then don't bother going vegan so soon. It's better to learn about what vegetarian dishes you can cook, so that when you do go vegan, you know how to substitute foods and such, otherwise you end up eating (like me) nothing but 2 minute noodles, and no other options at all.
Once you know that cadbury chocolate isn't vegan (I have picked it up SO MANY TIMES and checked the ingredients, on the hope that they have made it vegan) you don't have to check it again (unless you're desperate) same with other products (just chocolate is more important than other products

) but do re-check every once in a while to make sure that what you're eating hasn't had the ingredients changed.