HOW TO GROW FASTER
(with or without spending real money)

The first trick to growing fast is being as active as you can.   This will help with everything else below.

Try to make sure your building, research and training queues are always going.  I know this sounds hard you maybe dont have enough resources we will get to that.

 Dont let your stamina sit full use it.*  Participate in as many activities available as you can. Spend your stamina doing Radars, and Rallies.   Send a truck or trucks.  (dont be discouraged if trucks are attacked you will get less rewards but still will get rewards).   Run your secret missions, do the side content as much as you can all of it gives rewards.  This will help you afford the resources to keep things building and training.  You still might find its not enough we'll get to that later.

*the only exception to this is if you have an alliance event coming up and are trying to save up stamina for that.  Speaking of...

Participate in alliance events as much as possible.  Some of the best rewards are in these events.

Spend your currencies like alliance points on whatever you may be lacking to keep the queues going.   Maybe you just need a bit more gold to do that upgrade buy it from the alliance shop.  Maybe you have a ton of resources but all your queues are full, get some speedups and get something new going!  Also you can never have enough teleports so always buy those too.

Knowing what to invest in will help a lot as well:

Buildings to prioritize for upgrades:
Builders hut to build faster
Research center to access better tech
Barracks (focus on one or two to max level and use those to train the highest troops)
Drill center (for storing troop).  Keep these maxed before upgrading HQ so you can have a large and strong army
First Squad parking lot
Tank center (or whatever hero type your main squad is)

Dont invest into everything.  Focus on one main squad for example.  A little invested into the second squad is ok since its cheap but dont bother to max it out, its not much benefit.

Heros:
Same goes for this invest in your main squad and avoid investing into heros that are unimportant.  Prioritize leveling any UR heroes you find.  Skills included.  All the ones you'll find early are strong all game and will be worth investing in.

Research:
I proiritize
research speed
construction speed
troop attack strength
hero attack strength - again focus bonuses for the type of hero you are using like tanks
troop / hero defense is less important than attack but still worth investing in
boosting resource production can be useful

Try not to rush your HQ too fast.  Try to build your military and facilities up in a balanced way as you grow.  This will matter especially for the next part:

Finally, if you still find yourself needing more resources to keep your queues going, look for juicy bases to farm.  there are a lot of targets for smaller players out there that are loaded with resources.  This is probably the best and easiest way to get resources fast.  (well other than breaking out the credit card).  If you havent rushed your HQ and have a strong military it should be easy to find targets your size that you can manhandle and get great resource returns from.

Be patient and find the juicy targets so only a few hits will gain you the most reward.  If you start getting reduced rewards thats because the game will give you a debuff if you attack too much and you will need to wait for it to wear off.

I will post some tips on finding targets soon.