Go for something with a little give in it - not too hard, but not too soft either. A good mattress supports your body and conforms somewhat to the shape of it.
Coils vs. Springs vs. Pockets
This one’s a matter of the budget. Independent coil mattresses are the most expensive, but they’re a good buy if your budget can take it. If not, the other types will be cheaper.
It’s okay to haggle sometimes. As the proverb goes, ask, and it shall be given. We’re not guaranteeing you’ll get anything for having asked, but it never hurts to do so either.
Know the Budget
If you know what you can spend and what falls in that range, you can approach the situation from an unemotional position. If you see a bed that’s just slightly out of your reach, you can use your budget as a negotiating tool. You never know what you could walk out with.
Know the warranty. Figure out if the bed is really good for 10 years like the salesman says.