Influence is one of the currencies required to grow the stronghold. This is one of the slowest to build for most guilds as it has various limits to how much can be attained at once. As such guilds are always seeking more.
The main free way to get influence is to win SHEs. These can be difficult for those below level 70, but the smaller ones should be able to be done by nearly anyone above level 70. Note: Some classes like DC might have a harder time with this than more DPS related classes.
The downside to the free influence? Each character is limited to 400 influence from SHEs per day. You can run multiple characters if you would like to contribute more, and this is certainly appreciated. However this does start to take a lot of time. This is a balance we all work on.
Want to go a little faster? Thats where the vouchers and Strongboxes come in.
Vouchers come in many flavors, but the ones we are interested in here are Influence vouchers. They come in various strengths minor, basic, and major, but all do the same thing; add influence to a guilds coffer. They can be gotten from doing SHE's and from opening various strongboxes and chests. Like: [Stronghold Chest of Campaigns], [Regal Stronghold Pack], and the [Strongbox of Influence].
The downside here? A strongbox of influence requires a strongbox key and those generally cost 10-20k AD on the auction house (at time of writing), or 300 Zen for a set of 5 on the Zen Market. A little expensive, but worth it when you consider the time savings. They are filled with vouchers worth 2000 influence in total, which is a weeks worth of work for 1 character.
Influence is an important part of every guilds supply needs. Doing a daily run of 5 stronghold heroic encounters and turning in that influence should be attempted on as many days as you can. Runs are often started by high level characters so even lower level members can participate while they gain experience towards leveling.
Important note on influence runs... You can do more than 5 heroics in 1 day and still get credit. You work toward the daily max by accepting the prize using the CTRL-F button. If you accept 5 today and still have some leftover, just wait until the next day and accept another 5 then. You can build up a line of 100 or more heroics in your prize list.