So can somebody give me tips or something that will help the game last longer?
Option 1:
Play on a higher difficulty.
This is the most common answer, but has a fundamental problem: the AI doesn't get any smarter on the higher difficulties, it just "cheats" more. The disparity in production, research, happiness, etc. between you and the AI will get even larger. In the long term, the problem with this is that it often forces you to adopt a playstyle that isn't really what you might think of as Civ-ish, simply to overcome the massive disparity in resources.
Option 2:
Play a scenario game.
Most scenarios are built around an inherent imbalance. You're often starting off at a substantial disadvantage in starting resources, but the AI isn't given the massive extra bonuses you'd see in the first option. This sort of solution has limited replayability, though.
Option 3:
Download some mods.
Quite a few of the more popular balance mods out there rebalance the game to make things harder for the human player while, at the same time, removing some of the AI's advantages. This is not a contradiction; part of the reason the AI needs those bonuses is that the game's underlying architecture isn't really suited for the probabilistic way the AI makes its decisions. So, change that underlying balance, and the AI becomes much more capable while at the same time not needing the substantial bonuses that the default game provides.
There are quite a few options for this one, with the most popular (by far) being Thalassicus' "Vanilla Enhanced Mod / Unofficial Patch". Several other mods, such as my own, follow similar lines for their balance, so depending on exactly how much other content you want to add you have many options. As a result, playing any one of these mods might allow you to have the same challenge on King that you'd see on Emperor in the vanilla game, while at the same time having the AI using Prince-level bonuses instead of the default Chieftain values. This tends to make the game much more entertaining.
Option 4:
Go play Skyrim or Minecraft or something until the next big patch.
Nearly all of the major balance changes in Civ5 over the past year were first found in the more popular mods. So if you wait a month or two, chances are whatever balance tweaks you see in the big balance mods will find their way into the official patches.