Having just published a post discussing how veganism is not all about food, I'm now going to do another long (and maybe not so interesting to those of you who already have these things sorted) post on - you guessed it - food. It may appear to some that I'm feeding - pun totally intended - the idea that vegans are obsessed with food.* However, this is (as I've said before) the main area where most people will feel the difference.** Readymeals, for example, are a whole lot harder to get as a vegan than a vegetarian - this means cooking for yourself more. It might take more effort if you're used to heating something up, but it will also save you money. Swings and roundabouts.
Vegetables - you know your favourites and what you can afford/store. Fresh stuff can't be kept for that long, so it's worth having a few frozen and tinned things around. I normally have frozen spinach (for curries and pasta sauces) and peas (curries and a side dish for burgers or roast things) and tinned sweetcorn (for chowder or an extra chilli ingredient).
Beans - either dried (and soaked, boiled and frozen) or tinned. (I think you can buy frozen ones now, but haven't explored that avenue yet) Standards chez Duck are kidney beans, chickpeas, blackeyed beans and the tins of mixed bean 'salad'. These are pretty versatile and encompass many options for chillis, curries, salads, homemade burgers - you get the idea. Don't forget to recycle the tins! ;)
Dried things - beans (if you're ok soaking them), lentils, split peas (need soaking overnight before use), soup mix (to bulk out stews and casseroles), stuffing mix (part of a roast dinner), rice, couscous, pasta.
Tins - veg (as above), beans (as above), baked beans, mushy peas (if you like them)
Frozen - veg (as above), chips, burgers - not the healthiest, but sometimes you need something quick. The freezer is also useful for storing leftovers.
Jars - yeast extract (e.g. Marmite - a bit of extra flavour and b12), pasta sauce (more are vegan than you might think) - and hang on to the glass jars because they're useful reusable storage.
Flavouring - start with chilli powder, cumin and mixed herbs and go from there.
Baking things - flour and margarine (and water, but I'm assuming you have this on tap) are the basics if you just want to make pastry. For bread you need yeast (and preferably sugar and salt). Cakes require sugar and baking powder and a proper recipe - that's the only thing I haven't been able to ad lib on!
It's worth having a few meals in mind when you do a big shop (or get a delivery - worth thinking about if you don't have a car). This way you can take stock of what you have already, how useful it will be in the next few days and what you need to add to it in order to get everything to fit together. It also means that you know you are going to use all the fresh bits before they go off! You can get some great bargains with short-dated veg, but careful of buying anything that you aren't sure fits with what you want to eat in the next couple of days - if it goes off before you use it then it's a false economy...
*Personally I kind of am, but so are many omnis - and at least I indulge the obsession without eating whole baby birds or other animal products acquired in more-than-averagely horrible ways. That's a good thing in my opinion, as it helps to counteract the other false assumption doing the rounds that vegans are completely anti getting pleasure from food or indeed anywhere else. Rant over. ;)
**The exceptions being dietary vegans who are transitioning to full veganism. Bear with me, there'll be more about that soon.