There are so many factors that might be affecting your early game that they're somewhat difficult to list, but I'll give some suggestions:
1. Not working enough improved tiles/working towards improving tiles early on (especially resource tiles)
2. Not properly balancing the need to grow your cities and hence work more (hopefully improved) tiles with the need for early workers and settlers.
3. Not properly prioritizing techs and research paths to utilize advantages or address needs specific to your start
4. Not properly developing your economy! (This is the biggest adjustment necessary from other Civ games IMO) Cottages, CoL, Currency, even better understanding trade routes are useful here.
5. Not utilizing Slavery or Chopping when advantageous and appropriate to accelerate key settlers/buildings
6. City specialization is so important in this game. Gone are the days of building every building in every city and just spamming mines and irrigation. Learn which buildings your cities need and which ones they don't. Libraries in a city not producing much commerce won't do much, and a barracks in an interior commerce city with little production isn't that necessary either.
There are plenty of great game walkthroughs available on the site. Some are definitely written more for an audience very familiar with the basic mechanics and challenges of the game. Sisutil's earlier walkthroughs (on lower difficulty levels) are good, as are
Orion071's Noble walkthroughs. They are fairly detailed, and give thought processes and reasoning behind decisions.
In any case, there really is alot of information to absorb at first. It wasn't until I was trying to teach my girlfriend how to play that I realized how much I had learned about the game. And you are on the right website to get better. Just keep at it and keep checking in with the great community of players here and you will see results soon. The best part is, the game doesn't even REALLY get fun till you get to Monarch or so!