Dispensaries make stoners act like kids in a candy store: wide-eyed and ready to go crazy. Clinic bud is almost always better from street weed, which is why they will charge you more for the good stuff. Many smokers are missing out on some good product because the clinic seems too intimidating, but trust me, after a while it's like walking through your front door. If it is your first time, there is some easy prep you can do to make it seem much less like a mission and more like what you look forward to all week.
First off, all marijuana dispensaries are a little bit different. I have been into ones about the size of a small conference room and ones that basically fill up a warehouse. Also, depending on what state you live in, clinics can either be strictly medical or recreational. Medical clinics require users to have a medical recommendation or a "med card." There are a ton of websites and places to obtain one of these, and they are not that expensive annually. Recreational clinics simply require buyers to be over the age of 21, but depending on the place, will not except out-of-state IDs unless you also have a med card. There are pretty good resources to find this information about specific clinics, such as WeedMaps.
Before going to the clinic, think about what kind of weed you smoke the most (indica, sativa, or hybrid), what feeling you want to get out of your high, and how much your willing to spend. If you give information like this to the person behind the counter, they will give you options to fit what your interested in. These people are like the weed experts; trust me, I have friends who work at dispensaries and they know their shit. They try a lot of their product, so you can trust when they tell you whether a strain is what you're looking for or not. Do not be afraid to ask questions. These people often absolutely love their job, and love to tell you all their weed wisdom.
There are many, many, many, many different strains that you will be introduced to. Typically, the best weed is considered "top-shelf" or "private reserve." These are the most expensive, but holy crap, it is always such dank bud. I like to get a decent amount of top-shelf to treat myself every once in a while, when I just want to get really stoned and have it last for a while. You don't have to buy the best weed they have there, so do not feel pressured to. Feel free to start out with the med-shelf stuff and work your way up once you start to know exactly what you like, so you know what to really spend your money on.
There are many exciting new weed products you see in clinics that really are outside of the box. Do not hesitate to ask about them! I have found some of the best drinks, edibles, and funky stuff just by seeing is and saying "hey, whats that?" and I can tell you, it is so much fun to mess around with that stuff (in a safe way). But don't worry about the employees letting you go overboard; they know that marijuana affects everybody a little bit differently and have your safety and sanity in mind when you purchase.
Dispensaries are seriously like a magical weed palace where everybody is best buds and the love for the lifestyle is at its highest. They are not meant to be intimidating to new stoners, but are there to lead you on a path to maximize your smoking experiences and find new ways to appreciate the amazing herb.