My advice for you to save the maximum elixir is to fill your barracks completely before you log out. What this does is consumes elixir to put troops in queue within your barracks thus decreasing the amount of lootable elixir from your elixir storages (you can do the same with your Dark Elixir if you have Dark Barracks).
When you log in next time, just empty your barracks to get the 'stored' elixir back. Before unlocking the dragon, the most expensive unit per slot is the wall breaker. So what I would advise doing would be that you fill your army camps and when they are full, fill up your barracks with wall breakers and for any remaining space, if any, with archers.
Next is to discourage weaker players from attempting to raid your base and instead go for the win. This is done by placing your Town Hall way outside your main base. Often players will send a few troops to destroy your Town Hall and then walk away with only 1000 gold and elixir, and giving you a 12 hour shield (they know their troops are too weak to break in your main base and take your resources). In contrast, if your Town Hall is hard to reach for weaker players, chances are they won't attack and a stronger player will come by instead and take everything.
EDIT: With the 2015 update to shields and loot storage, this is no longer viable.
My last piece of advice here would be to rearrange your base when needed. You have a few storages and it is not easy to protect everything. Certainly though, you can protect a few more than others at any time. When you need to save elixir, put your elixir storages more in the centre of your base where it would be better protected and move your gold storages further out.
I personally am not a good fan of waiting for my collectors to get the resources I need. I get most of my resources through raiding other bases. My advice now for how to do so:
Don't be afraid to tap NEXT
When you are raiding for resources, you really should not care about trophies that much. The best use of trophies at this time would be if you get a nice loot bonus or if you are going for the achievements to get some gems (so that you unlock another builder if you haven't unlocked them all yet). This brings me to the main point: look for bases where the collectors and mines are full. They are not always easy to come by, but a single raid for such bases usually gives you 200k of gold and elixir or more and you don't need expensive troops to get them.
Paying a few gold and wait for the perfect opportunities are well worth it. If you find a base with little to no resources, it is best for you to skip and find another to raid.
Send your barbarians and archers to attack those filled up elixir collectors and gold mines. Such bases have usually be abandoned anyway, so you are not doing any harm. Even if you don't win the raid, you will keep the resources.
I will also share this video from a youtuber I follow for this nice video about raiding with examples of full and empty resource buildings and some raid examples: link