Well this is 90% of the game for most people. Account building is where you create something from nothing that relfects you and your strategy. It is also where 90% of people lose the game. A weaker account can still mix it with the best if it is set up correctly, but more importantly, if it is growing/improving.
There are a few things to consider when building which are ascending, farming and warring.
Your ascension level is reasonably important. Lets face it, a TUK (the unknown) is obvioulsy the best as it has the highest bonus (47%) and AB (59%) but it IS NOT essential. The first 6 ascensensions to LG+1 are where you get most of your bonus (30/25) and each level after (next 17) that give only minor improvement (1/2). Once you attain LG+1 you basically have enough under your belt to be competitive, but most people continue until they get to a name they like (eg God of Ancient Gods) or max out. Now you can either ascend the old fashioned way (build, get GnR, get requirements, ascend), buy levels from the BM (cash) or buy an account on the main forums (cash/naq). I would highly recommend the latter as there are many superior accounts around going cheap but if you are attached to your account easier and cheaper to buy from BM (for $10) as it wont reset your account and it is actually cheaper than the resources needed (esp for the higher ascensions). Now if you have a decent covert level (as one should have anyway), bank space shouldnt be a problem. If your are using cash to buy with, simply farm and fill your bank, go to norm and sell it all to cash spenders, rinse and repeat until you get what is needed.
Farming is self explanitory. To grow, every account need resources and honestly, income just wont cut it. Get a good regime going (see the farming topic here in the FAQ) and rake in the naq. Here you need to consider who you are farming (ie what you are coming up against) and what build you are on. If it is your final build (ie buying ascensions/finished ascending) it is best to have a heap of small strike planets. This will allow you to maintain your attack cheaply and free up UU for other areas. Example a TUK can have a 1T strike from 2.5 mil SS, if you have ten 100b attack planets, you boost up to 2T, that goes up to 4T with AB, up to 8T if you have a big enough MS (4T strike) to cover it. There is only one natural def in perg that can stand up to that and to build that naturally, you need 20 mil supers and weaps. If however you are not on your final build, I wouldnt recommend farming over many defs and would say to have 10 50-100k UP planets. That way you always have plenty of UU to cover losses from farming and ascending.
Warring requires two things, knowledge of game mechanics and the ability to identify weaknesses in other accounts. Sure a decent UP helps so you have UU to burn, covert levels to sab/defend, strike to farm/kill their def, ultimately all mean nothing unless (for lack of a better word) you have a bit of mongrel in you. The main thing to remember is only build what you can afford to be taken, ie dont make planets/defs to big. Any planet you build should be only big enough to make a difference, not a game changer it you own/loose it, and defs stould be able to be rebuilt in an hour, not over the next week. In doing this, you reduce any (percieved) weakness and reduce likelyhood of potential attacks/drawn out war. Any spare naq you have is best put into your "untouchable" stats, like cov levels, MS capacity etc ie things that are still very useful but are permanent for your account.
So I'll refer back to my opening comment that account building where 90% of people lose, and clarify that it is because they BELIEVE they have lost. So really what I am saying is build what you want, but build with goals and others in mind, have fun doing it and you can make any combo work if you put your mind to it (some just work easier than others)
