Also, please avoid tight tubes and tunnels, because they are extremely hard to clean out and your hamster can even get stuck in them. If you want tubes that extend outside the cage, research, and try to find the safest option. The temperature and activity (even the smell) I believe, can depend on species, age and sex.
Please avoid wheels with gaps in them as your hamster can get it's foot stuck while it's running. Research wheels as the size requirements vary for different species, and some key things to remember are:
It's best to get a silent wheel as they tend to run a lot in the night (especially robos despite their size)
No gaps
And make sure their back doesn't curve. The wheel should be big enough for your hamster to use with no curving to the spine.
I believe it's best to not use hamster balls as they have breathing holes that a small hamster foot can get stuck in and they often aren't big enough for a Syrian to use without it arching it's back (at least in my case). It's better to get a play pen or to line the bottom of your bathtub with blankets and toys, and play with your hamster there. This way you will get a lot more interaction. Also, don't bathe your hamster as it can be very dangerous. I they often can manage cleaning themselves, but long haired syrians can get matted fur if it isynt maintained properly. Also, avoid hamster playdates with hamsters (especially syrians). Due to territorial aggression they can pose a serious threat to each other and can cause damage. You can house dwarf hamsters together but it is not recommended. Again, please correct me if i've made any mistakes.