First, I don't consider myself an expert at all. Not that long ago I was in your same place. I have not got a pretty good record on Warlord and have moved on to Noble.
The most important thing that helped me was to quit trying to play every character and being good at all the traits. Find a trait that you are comfortable with and stick with that. You then can set up strategies that will work in multiple games and give you benchmarks to reach to help you judge your own play. Personally I like Finacial civs. I am most comfortable running a cottage economy and so getting the extra gold is a big help.
My second tip is to calculate the food for your cities before you found them. This might sound tedious but I have found it extremely helpful. I now can look at a potential city site and know how many farms I need to grow fully. Also keep in mind that Biology will give your farms more food so you might be able to put an extra cottage instead of a farm. This could end up helping a lot once the cottage is mature.
Third, know your neighbors. This is really important. Some civs have a tendency to attack no matter what, e.g. Monty. While others would rather just build wonders and tech and trade regularly, e.g. Mansa. Then you have the ones like Toko that likes to build tons of cities, will rarely trade, and could attack at any moment. So, once you meet the other civs you will have the idea on how much of an army that you need.
Lastly, don't forget your army. It is important to keep track of your army. You need to make sure that they are up to date, i.e. no warriors when you could have maces. Also, make sure that they are in the right place and/or they can move through your empire quickly. For example, if Monty is right next to you, then you might want to keep a majority of your army near that border so that when war is declared you can respond quickly. I am not a warmonger by any means, and early in the game my army is usually very small, but once I get to maces I have at least one city that will start pumping them out constantly. Also, don't forget to use good defensive units/upgrades in the cities. Longbows and rifles are my favorite early and mid game defense but once I get railroad for machine guns I try to have a couple in each city.
Wow, this turned out to be a really long post. I know when I was looking for advice playing I was always looking to understand how others thought while playing. I hope that this helps. Also, if any experts read this and see glaring errors please point them out. The last thing I want to do is give out bad advice.
Good Luck.