A lot has changed with this game since I started posting here. When I started, I was about level 30 with crappy stats. Now I am level 90 with 300k stats. If I were to start this game over, here is how I would do it and it is totally free:
1) proceed to about level 10 and plan on stopping for about a month or even more if you are content.. If you can level to 10 by only doing Limited time quests. These quests yield the best units for free. Then do not do anything until you have leveled up buildings expanded your kingdom and expanded your vault. Early on when income is slow this is difficult to be patient to do but it will pay off huge dividends later.
2) for early defense, get your magic academy to four and get illusionist, but if you are content to start real slow just start leveling your siege academy right away. You will eventually want to get this to ten to buy flaming catapults.
3) always have maximum allies and maximum units for your level. You have an allowed amount of 5 allies per level (level 5 = 25 allies) and you should have 3 units (illusionist or flaming catapults) for each ally. Thus at level 5 you should have 75 units. You also need to purchase armor and a weapon. I recommend purchasing the cheapest ones with attack and defense. Weapons and armor have the lowest cost/benefit to your stats, but I think you win more battles and lose fewer units if they are equipped with something. My recommendation is that you don't move forward at this point until you have all of the allies, units, weapon and armor unless you are doing a LTQ that is yielding 100+stat indestructible units. There used to be a good strategy to fly under the radar by having few allies. This simply is not the case anymore.
4) get in a guild as soon as possible. Early it is good to find a good camping guild to get bonuses for upgrade time and speed.
5) the best way to find allies is off the forums or by visiting other kingdoms using the invade button and looking at their stats. In the very early going you can earn 625 gold a day by visiting up to 25 allies. This is great money in a pinch. It is ok to get extra allies (you can have up to 500), but be careful to not satisfy any quests that will make you level faster than you want.
6) Depending on your play style and how frequently you play, depends on what buildings to upgrade. Personally silos, leatherworkers and stables are the best to upgrade early. If you can be patient enough to upgrade all of these to ten before moving forward, you are a better person than me, but you will have an awesome income to build in future levels. Personally, I wouldn't worry about upgrading any others. These yield the best income and are relatively inexpensive to upgrade, but the high level upgrades take a while. Do not worry about income per hour. Cottages yield the best income per hour, but you will never see more than half of it.
7) once you get 150 flaming catapults ( or somewhat less if you already earned some indestructible units) with armor and weapons start moving forward leveling only with LTQ. The best LTQs are ones where there are about 40 levels and you kill monsters in the various maps. At a low level you won't be able to progress far but your rewards for your level will be amazing.
8) up until level 40, I suggest putting all skill points in hero strength. This will allow you to get furthest in the LTQs. This means saving one skill point every other level and adding one hero strength one level up and then adding two the next level. The other three items are important, but at this point raiding yields little so stamina is not important and since you have the best free units possible your attach and defense is going to be pretty good. So you will probably not be messed with. As a free player you will not have the best stats, but the more patient you are, you can have better stats than many gems spenders. Attack and defense points are also useless at this level as yours stats will be good enough to get you by.
9) some people will recommend camping at 30 to build a defensive wizard army, but I say move forward to the bigger prize at 40. Again make most of your leveling through LTQs to get all the juicy units.
10) Level 40 is another camping level to get your gnomish lab to 10. Along the way to level 40, it might be good to use upgrade time on lumber mill, engineering academy, and water temple of healing. The lumber mill will reduce the cost of expensive upgrades to come, the engineering academy will boost the stats of your flaming catapults, and the water temple of healing will reduce casualties for when you start raiding.
11) at level 10 gnomish lab you unlock the blackrock battering ram with whopping 148/95 and the invasion cannon at 300/183 these units are expensive but they are among the best free units in the game. At 20k a piece, it will take some time to acquire a full army, but this is where upgrading those buildings pay off. If you want to be patient here and get them all now that is certainly fine. Personally, I would take advantage of any LTQs to get awesome units. And at least get to level 41 to unlock your manors.
12) after level 40 I recommend putting skill points into stamina until you get to 20-24 stamina. After this I would keep adding to hero strength. The LTQs are just too important to get as far as possible.
13) without a doubt raiding people pays better than waiting for buildings to collect. A good day raiding can bring in over a million gold. Once you hit level 40, you are looking to hit leatherworkers 9 and above, lenders 4 and above, any manor, any level 10 silo, any playhouse level 5 and above, any in level 8 and above, any shipping yard level 9 and above. I once found two level 10 manors and brought in over 600k in six hits. Over vault people will be rare with new vault increases. Money buildings winemakers level 6 and above and gold mines level 5 and above.
14) personally, at this point you are looking to raid and do LTQs to max out your army, just make sure you are keeping up with allies and cheap equipment. If you have extra buy better armor, but this is truly a last priority.as far as upgrades, I would look to upgrade lenders, manors, playhouses, inns, boost buildings in your preferred order.
15) any more tips?