Start small. Don't feel you have to be fully prepped immediately. It won't happen that way.
So, assess the priority.
1. BUG OUT/GET HOME BAG
First, probably best to focus on a Bug Out/Get Home Bag. This can be as simple as a backpack with some water, some food (that doesn't require cooking and will keep for a while), some basic first aid supplies, and anything else you need to get home (as a SHTF event may happen when you are not at your home base). If you have no home base, then a Bug Out Bag (vs. a Get Home Bag) will need a bit more gear (such as hunting/fishing gear, fire-making gear, shelter supplies, etc.).
2. WATER - Easy and cheap to stockpile, and the NUMBER ONE item on any prep list. Best to have a way to replenish this, like rain barrels for example. Still though, whether bottled or just filling up some old milk jugs, it is an easy prep.
3. FOOD - Just buy a little extra each trip, and put it away. Canned foods can keep for a couple of years, some others can be kept for a decade or more (if you store them properly, like mashed potato flakes, dried beans, dried corn, rice, etc.) Learn what is around you. Insects, frogs, birds, fish, snakes, etc. Many food plants grow naturally also, just be sure to learn these from a pro (as some poisonous ones can resemble edibles). Stick with the more obvious ones (like fruits) for your area.
4. WEAPONS - Firearms are ideal, but any weapon is better than none.
5. MEDICINE - If you don't take them regularly, stock up on Over The Counter ones. If you can get any others (old prescriptions, etc.), not a bad idea to keep at least. Medicines lose potency over time, but something can be better than nothing.
6. SHOES - This was mentioned above, but having some good shoes that last a while is often overlooked, but very important. While a survivalist could cobble some shoes out of just about anything, nothing beats the comfort of a well-engineered professionally made boot. Expensive, but may want to have some spares.
7. VISION AIDS - If you wear glasses or contacts, having spare ones is a great idea. zennioptical.com has some really cheap ones (cheap price, but well-made, and I mean CHEAP). I got my entire household glasses from there, and no complaints.
8. BARTER ITEMS - Think of something you don't need/use, but that could be valuable to others. For me, this is cigarettes.