Those new to vegetarianism often don’t realize how many animal products are in the foods they consume. In fact, I was vegetarian for several years as a teenager before I understood the concept of animal rennet. At that time, there were no cheeses available with non-animal rennet in our local supermarket, so maybe it was best I didn’t know!
Products that contain Gelatin are also commonly missed by new vegetarians e.g., marshmallows, some yogurts, jello. A third category, is things coated in “confectioners glaze” like chocolate coated almonds, or chocolate covered raisins. This glaze is made from the secretions of an insect. If you still eat honey, then you’re probably going to still be ok with eating this glaze, unless reading about it completely grosses you out and puts you off.
A huge fourth category contains beers, wines, and spirits. Often animal products are used in the filtering process and other aspects of the manufacturing process. As with most things, it used to often be quite difficult to get accurate information. These days, thanks to the wonders of the internet which provides us with increasing access to knowledge on living a cruelty-free lifestyle, this information is becoming much more readily available. There are even some retailers who are routinely making the vegetarian status of their products more obvious with a vegetarian/vegan symbol.
Transparent labeling will surely increase awareness of products that aren’t vegetarian-friendly, and increase demand for those that are. Some sites even allow you to search for vegetarian or vegan wines as a category, so you’ll know which options you can choose from and not need to wade through individual listings only to find they’re unsuitable.
In all my travels, the UK is definitely the leader in food labeling in terms of labeling products as vegan or vegetarian. The standard supermarket chains in the UK, use helpful symbols on most of their items. In contrast, only specialty supermarkets like Trader Joes tend to do this in the US. However, customer service reps usually have the information you’ll need available if you phone (I tend to do this more with beauty products like moisturizers, rather than food products). Australia and New Zealand are even further behind, with only a minority of products labelled and customer service reps often not having the information about whether their products have animal-derived ingredients.
Spontaneity can be a little bit harder when you’re out enjoying a beverage at a bar or at someone’s home. However, there are some resources that will allow you to do a quick check on your smart phone. This site is definitely a leader in this area, and will be comprehensive enough for most of your needs. In very vegetarian-friendly places like Portland and New York, you’ll find some bars are completely vegan friendly, and this is a great treat for us visiting vegetarians.
Pairing wines with vegetarian dishes is also a skill you might want to read up on as new vegetarian if you’re wanting to explore more fine dining vegetarian options rather than just eating vegan chicken nuggets and tofu scramble 
Photo Credit: Creative Commons, jean-louis Zimmermann
