Outpost Upgrade Guide
Below I am going to list my personal preference on building creation and upgrades. I will also give a brief description of why a given building has been put in this location. This is guide has worked well for me, although you may want to modify it slightly based on your own play style. This guide does assume that your Monsters are fairly well trained/upgraded. This will work in outposts regardless of the quality of your main yard as outposts are not restricted by the level of your Town Hall.
BUY STARTER KITS! I cannot stress this enough, always buy the most expensive starter kit that you have storage space to afford. Starter kits are not only a major savings on resources but also on time.
Housing, Flinger, Catapult
In an Outpost the buildings above all share the #1 spot in priority in my mind. When you upgrade your Map Room to level 2 you need to get ready to attack. Any of these structures not being at the maximum level holds back your ability to attack.
Monster Bunkers
The best defense is a good offense. Level 4 Bunkers can hold 4 D.A.V.E.s with the lab ability giving Rocket D.A.V.E.s the ability to shoot oncoming attackers from range this makes them harder to bait out and destroy. With 4 D.A.V.E.s in a bunker there will still be 20 spaces left over, in my main yard I add a Bandito, in outposts I don't worry about this. Another great thing about having Rocket D.A.V.E.s in your bunkers is that they can shoot down any flying monsters making your Bunkers also act as Aerial Defense Towers. Another effective strategy is to use both 3 Rocket D.A.V.E.s and 3 Airburst Eye-ras While the Eye-ras can be baited out and destroyed first the 3 Rocket D.A.V.E.s backing them up will make this more difficult.
Resource Gatherers
(Twig Snappers, Pebble Shiners, Putty Squishers, and Goo Factories)
This may seem odd that this is second, I know that without resources you cannot build anything and for your main yard you should upgrade these first. In your outposts, especially when you have several, you will find that upgrading the bunkers to cap first is great so that you do not get taken out by wild monsters while the resource gatherers upgrade. Take them to level 10. Resource Gatherers have very high hit points at level 10 and can slow down attackers and allow your towers time to take them out.
Fortification
This is the only thing in this list that I would not say needs to go to the level cap immediately. Fortify early, at least level 1. Oddly level 1 fortification takes very little time and resources and being that level 1 is a 20% damage reduction and level 2-4 are all 10% each getting that first level on your Towers makes the biggest difference. in addition to your defensive towers the Outpost building itself can also be fortified.
Railguns
Infinate firing range, need I say more? Railguns line of fire can hit monsters that are no where near the attackers that are coming for them if they are in this infinate line of fire. For outposts Railguns are very overpowered at level 6 as thier damage is capable of killing anything that is not a champion in one shot. If you follow the link to the Railguns page there is a video at the bottom that demostrates this.
Aerial Defense Towers
If you are being attacked by players using Zafreeti and/or Fomor the importance of these towers increases dramatically as they have very high damage, although they cannot fire on anything that is not flying.
Laser Towers
Upgrading your Laser Towers early will help to balance your resources a bit as both Railguns and Aerial Defense Towers have a higher pebble cost. An alternative would be just to catapult your twigs away while you upgrade Railguns and Catapult your Pebbles while you upgrade Lasers. To me this is inefficient, being that this is a strategy game effecient is what it's all about.
Tesla Towers
Range. I would put Tesla Towers above Lasers in priority if it were not for the issue of resources. At higher levels Tesla Towers become more and more devastating because thier damage and number of shocks per charge both incease as the structure is leveled up. As for the resource issue that was discussed earier Tesla Towers use more Pebbles than Twigs at lower level and change to more Twigs than Pebbles at higher levels, you should not run into the same issue.
Sniper and Cannon Towers
As long as you bought a starter kit these structure were (at least most of them) built for you. I put them last on the list to take to maximum level because the defensive effectiveness of the other towers is really much better. Sniper Towers have very high hit points, and may be placed near other Towers that you do not want easily taken out. For Example placing towers such that a crowd of Ichi would first need to destroy a Sniper Tower before they got to the Laser (lowest tower hit points) behind it is wise. This being said make sure that this does not cause your base to be prone to catapult attacks. Cannon Towers are slightly more effective in my opinion than Sniper Towers because of the splash damage, this is much more devastating at higher levels as well. The way that splash damage works is that the Cannon Tower hits a particular target for maximum damage and any monsters in the splash damage radius will take a % of that damage. Cannon Towers can hit an unlimited number of monsters, although if the monsters are spread out the monsters on the outside of this splash radius will take little to no damage from the shot.
Yard Planner, Hatchery Control Center, Monster Juicer
If you have gotten this far and not built the buildings above now is the time. The Yard Planner should likely be built early on for layout purposes, although I have seen some great outposts built without it. The HCC and Monster Juicer both have low hit points and are only there to extend your never ending chain.

