(requested move to Strategy & Tips forum)
Do you have BTS? First thing I recommend is playing BTS as it is the definitive version. If you don't have it, get it.
If you are really struggling on lower levels, then you probably have some important basics to learn. I recommend playing Pangaea maps for now. The map will allow you to immerse yourself into most aspects of the game including diplo at early phases. Play standard settings - normal speed/standard size. Try not to get too crazy on the settings/options for now, and I would suggest playing without huts/events as well. Overall, it is better for learning and easier to get advice and apply it.
Here are a few key basics and ideas:
1) Post up a game as described above and play a shadow/learner game (in S&T) ..you will get a lot of helpful advice as you play
2) Civ IV is very much about doing well early game such that things snowball later. Playing poorly in the early game will cause problems later
3) Workers are the most important unit in the game. Almost always, worker is the first build of any game..there are really few exceptions to that rule, and mostly apply to some coastal starts
4) Worker management is highly important, especially early on and really always. Improve the right things first and chop forests..avoid unnecessary roading
5) Granary is the most important building the game, and really the only building required in every city (exception may be strategic city placement where food is not present) Do not waste precious time building useless buildings.
6) FOOD is KING. This is absolutely THE golden rule of the game. Food drives growth and production. Food actually IS production. (improve food specials first and tech accordingly)
- Generally food is the key driver on where you settle your cities, and you want to settle such that food or important resources is in the first culture ring so you have access immediately to improve and use. (Creative trait though gives you some flexibility here)
7) Slavery is the most powerful civic in the game. Learn to use it. Slavery turns food into production. Mastering the use of slavery and related hammers is one of the keys to increasing difficulty (Bronze Working is almost always teched right after the food is taken care of..heck it might even be your first tech if your starting techs are applicable)
8) Maintenance is a key factor limiting growth and expansion (city, distance, unit, civic, etc.). It increases with difficulty and puts a limit on expansion early on....(see below)
9) Don't be afraid to settle cities closely..that is, overlap cities. First, it reduces distance maintenance. Second, it allows tile sharing which helps with worker management and cottage growth for capital. Cities will be whipping early anyway, so you don't need every tile in a city improved. They can share food, mines, cottages, etc. (citizens can be adjusted between tiles in the city screen)
10) Early religions are not important for the human player. Do not waste beakers on early religious tech paths. Again, your focus should be a worker techs, then writing and so on. Very common mistake of new players thinking they need to grab an early religion. Just let the AIs waste their time on that. You will likely get religion spread from them anyway, and can grab your own religion later when they come from far more important tech choices.
11) With that said, choose tech paths with a purpose and learn about AI priority techs. That is, AIs tend to focus on certain tech paths (religious, iron working, calendar, feud, machinery - basically military techs). Knowing this allows you to avoid wasting beakers on techs that you can easily trade for later.
12) Trade routes are important. Make sure you have internal trade routes set up immediately between your cities, and note that you don't always need roads if a river is in place or even sailing if the coast is in your borders (hard to explain this without showing) Furthermore, foreign trade routes are more lucrative and should be accessed asap after Writing, if possible. Can be map dependent on how soon you can get this set up.
13) Commerce is an important component of the game. (Commerce
is not the same as Gold
). Commerce drives the sliders and produces beakers, gold, culture, and espionage (BTS) depending on your sliders. You want to generally always focus slider on beakers, ofc. Until you settle your first city (and start deficit research) you run 100% science. After your first settle, maintenance kicks in. Start getting used to running 100% tax vs. 100% science, as opposed to getting caught up with a certain % in between. In other words, run 100% tax until you can fund the next tech (just do the math). Later you have more options to acquire gold, so this changes, but it is more optimal early before you get beaker multipliers in place (libraries, academy).
14) Diplo is important. Learn who the players are. The leaders are different and have different coding on how the respond to others and the human. Some are religious zealots(Izzy), some are ..well..psychos (Monty, Rags, Shaka). Some are much more peaceful and open to you - trading and stuff. One (Toku) is isolationist. Your approach to them can and will be different. And you can leverage certain leaders in certain ways. Be wary of adopting early religions unless you are comfortable in the choice - security, relations, etc. Religion has its uses, especially with the powerful civics, but it can make you a target.
15) Great people are important. Learn to use them. Great Scientists are the most important in the game - at least early to mid game. You want to get up a library soon after writing and start running scientists to get your first Great Scientist (GS). The best practice for now is to use the GS for an academy in your capital, which often is setup to become a powerful Bureaucracy (civic) capital.
16) Lastly, just keep in mind that you have a lot to learn but try to put more thought and focus in your decisions, especially early on. You don't have to, but this is certainly a game where more attention to micromanagement helps toward success.
If you have or plan to get BTS, I recommend installing BUG/BULL and/or BAT mod. UI/Info mods that most use:
https://forums.civfanatics.com/forums/civ4-bts-unaltered-gameplay-bug-bat-and-bull.268/
One other piece of advice: I recommend focusing mainly on the early game right now - like the first 100 turns on normal speed. Just get accustom to the basics while learning to expand and grow your economy, while learning these basics. Also, Currency is a very important tech in the game and one that you want sooner than later - one way or another. Given how slow the AIs tech on the low levels you play, you will likely tech this yourself. After Writing, for now, I'd recommend a Maths>Alpha> Currency path or Alpha>Maths>Currency. Currency not only boost your economy, but allows you to trade extra resources for Gold per Turn (GPT) and trade old stuff for gold. You can also build wealth. (markets on the other hand are not important - avoid)
edit: Ugh..one more thing to answer your question. Leader is really not important. There are better traits certainly that others, but unless you know how to leverage them it really does not matter much to you now. I'd actually for a new player would find the Civs starting techs more important. (Things like Agriculture, Mining and The Wheel are good starting techs)
Passively though, traits I think that can help a new player without much thought are the Creative trait and probably Charismatic, just for the extra happiness. Expansive is nice too.
(Unfortunately, no Crea/Char leader).
So, I'd recommend Washington as a good generic leader to play. Charismatic/Expansive is a nice trait combo, and the Unique Unit and Building are very late, so you don't have to think about them. (And really Uniques are inconsequential to your game right now) American starting techs are decent and flexible. Hatty of Egypt is probably another good option - good traits, great starting techs, flexible settling due to auto border pops.