Equipment
The key question you need to ask yourself is, “what are my goals?”. Then choose a gym whose equipment matches your goals. So if you’re after muscle growth, choose a gym with ample free weights (dumbbells and barbells, cable crossovers, benches with both flat and incline options, squat racks). And if yoga and stretching is your thing, you need a gym with a yoga studio and plenty of space for stretching.
Check out the layout of the gym. Does it feel energising to you? Is there space to move around? Is the balance of equipment right for you? Personally I don’t like vast rows of treadmills as far as the eye can see, with little alternative cardio equipment (cross trainers, bikes, rowing machines). And I hate small cramped free-weights areas, I like my free-weights areas to be spacious and a good distance between weights benches to avoid bumping into the person next to you. I’ve been in some gyms in Australia where the free weights areas were awesome. Less so in the UK.
Another thing to consider is the music in the gym. Do you want loud music, or do you prefer to work out in a quiet atmosphere? One gym I used had 2 floors with an open mezzanine, with loud rock music from the upper level clashing with the loud pop music downstairs, which was massively irritating to the ears.
Staff
The first people you’ll probably see are the reception staff. Are they welcoming, friendly, knowledgeable? All these things count for a lot if you’re going to interact with them every time you come to the gym.
Then consider the availability of gym instructors and personal trainers. Are they available, attentive, and approachable? Talk to them and you’ll see.
One thing that put me right off one gym I visited was reception staff eating doughnuts, painting their nails (and that was just the guys), and when I left, I saw one of the gym instructors standing outside smoking a cigarette. Ugh.
In contrast, my current gym has friendly, lively, chatty and knowledgeable staff. It makes such a huge difference to your gym experience. All the personal trainers and gym instructors have their photos on the wall, with a brief biog about them. I chat to them about the latest workout trends, nutrition tips, and they’re all really knowledgeable. So when you visit a gym with a view to joining, try chatting to some of the staff and you’ll get an idea of how friendly and knowledgeable they are.
Showers & Changing Rooms
This is where most gyms let themselves down badly. The changing rooms are often cramped, with small/narrow lockers which are a struggle to get all your stuff into. Once I took a sports bag to a new gym only to discover that locker was too small for the bag to fit into.
Always ask to see the changing area (and showers too, don’t be shy), and look out for broken lockers, cleanliness. One gym in East London I checked out (and didn’t join!) had a changing area littered with sticking plasters, cotton buds, empty drinks cartons, chocolate wrappers.
In contrast, when I spent a year in Australia, I joined a gym with the cleanest and most spaceous changing area imaginable. The lockers were double width to fit the largest of sports bags, and a light even came on inside the locker when you opened it.
And always ask for a free trial session, so you actually experience the changing area and showers rather than just a quick glance around. Try before you buy, this gives you a much better chance of spotting problems. One free trial I had was great, until I used the showers at the end. One cubicle had only freezing water, another had only scalding water, and the third had no shower gel in the dispenser.