Building a killer base is not intuitive; answers to the following questions are tricky:

"Do I build many towers or a few big ones?"
"Do I build lots of different towers or group similar ones?"
"Storms or Mages? Lightning or Trebuchets?"

I'm shocked at how many players (even in Diamond league) have weak, runty bases (for their level). It is not hard to have a base with over 150k defense before level 50. Let me tell you how it's done. Also, come check out my base anytime (it's not perfect, I had to restart my process three times as I learned more (*facepalm memory*). You can even attack me and I won't be offended, just please don't do it when I have a lot of resources stored up and please provide me some feedback! See the bottom of the post for how to see my base if you don't know how.

Step 1: Don't build Ballistas. Just stick the ones you already built in storage. I have like five in there, it's okay. Keep your farms next to your castle on the big island.

Step 2: Put your upgrading buildings (get Elite so you have two) BY THEMSELVES on your outermost island. They won't occupy boosted space this way. Swap out whatever's cooking regularly. .....

STEP 3: Grab two Archers and max their level. Just pour lumber into them repeatedly until maxed, ignore everything else. When you have enough wood to buy another level, use timers on the one closest to finishing to finish and immediately buy the next level. Ask your team for lumber to get there if necessary.

STEP 4: When you hit a bottleneck, upgrade your storage/builder/farms/lumbermills so you can continue leveling your archers. THE ONLY OBSTACLE THAT SHOULD STOP YOUR TOWER LEVELING IS YOUR BASE LEVEL.

Step 5: Once you are leveled as high as you can go until you level your base, put your max level Archer(s) at the front of your long island (10 spots).

Step 6: Repeat STEP 3 with your Cannons. Put the Cannons behind the Archers.

STEP 7: Your base has now leveled a bit, so go level your Archers again with STEP 3 & STEP 4. Then level your Canons again.

Step 8: Now you have 2 Max Level Archers, and 2 Max Level Cannons. Do STEP 3 again, this time with a Blue Mage and a Red Mage. Get them to 3 levels lower than your max. Do this with two Storm Towers, to 3 levels below their max.

Step 9: Do STEP 7 again. Then STEP 3 with Trebuchets. Then STEP 7 Again.

Step 10: Now you should have a 10-place island with Archer - Cannon - Treb - Blue Mage - Storm, and Archer - Cannon - Treb - Red Mage - Storm

Step 11: Repeat STEP 3 with (3X) Lightning Towers. Then STEP 7 with everything. Then STEP 3 with two more mages, followed by STEP 7. Put three Lighting towers on a small island. Put the Red and Blue Mage behind them (three levels below max).

Step 12: Max a Treb and place next to your farms on the home island with either 3x Lighting or Archer/Cannon/Treb backed by mages/storms at the front of it. All done! Add new islands only when you have maxed the hell out of everything on the first three islands. Boost everything all the time, STEP 3, STEP 4.

If you follow these steps religiously, your base will be 2-4x more powerful than anyone your same level. You will be attacked less, you will easily accumulate more resources and hold onto them longer, which will in turn make you more valuable to your team and more able to level your bases when you want because you'll have plenty of resources lying around. Even better, other players will fear your ridiculously powerful towers and leave you alone. You won't even need more tower space or islands until probably level 120 or so, seriously.

FORTIFICATIONS EVENT TIPS: it's okay to go off the 12 steps slightly during fortifications events, follow the tips below.
Extra Tip 1: Level your Dragon Den during fortifications events, and RIGHT AT THE BEGINNING OF THE EVENT. Then immediately attack a bunch of players to refill your lumber. During the event, you will have a hard time finding more lumber, so the boost at the beginning of the event is crucial before many players have spent all their lumber.

Extra Tip 2: Level lumber mills during the fortifications event, too, as they use Meat instead of Lumber to level, and lumber is hard to come by during the event. Also, farms and lumber mills use a fair amount of resources quickly, so you can score points fast without having to use speedups.

Extra Tip 3: Save up your 12 hour speedups before you level your Hatchery, Breeding Castle or Storage, they can take weeks to upgrade and it's just torture to wait that long.

HOW TO SEE MY BASE: From your base screen, click on the message center in bottom right, click to compose a new message, type in "Salamanca" in "To:" line, and "Base Check" in the subject line. Then go to sent messages and you'll see me there; click on my picture and click the attack button and it will bring up my base, defense, best dragons, etc.

I close with this:

Grant me the serenity to accept the disadvantages I cannot change,
The courage to exploit the arbitrage in other players that I can,
And the wisdom to know the difference.