Note: my question is specific to the LMoP adventure. I am not asking for general advice on motivating players.
I've recently begun a new campaign in 5e with my group of players. We are all new to 5e and so far it's a great system and a welcome change from PFRPG. When we played Pathfinder, we ran a published adventure path (Rise of the Runelords if you're interested) and the adventure was very much so "on the rails."
Now that we've switched to 5e I decided to homebrew the setting and adventures, but having never written my own campaign, adventures, or setting, I've been looking to The Lost Mines of Phandelver for idea generation and using it as a general template.
One of the problems I'm dealing with is chapter 3, in which LMoP has a somewhat freeform section where the PCs go about doing various quests for people around town for no apparent pay and then only after they do the job are they discretely rewarded with faction ranks. Well, my players will probably never take on a job like that if they don't get paid -- they might turn it down simply because they don't know what it pays up front. When I tried to use some of the jobs from LMoP they simply turned down the jobs offered and said they had better things to do. I ended up having the NPC pay them for the job in the end.
The benefit of doing these jobs in the starter set adventure is that the PCs gain renown and faction ranks. I want to give my players' PCs faction standing but it's difficult to get them to take the bait without laying out the benefits of why they should do so before hand and without pay -- and pay is not mentioned for these jobs in the LMoP adventure.
How can I get my players to stop being so greedy? How can I get them to bite the hook for these jobs without hard cash up front? I'm especially interested in answers from DMs who have run LMoP and know which section I'm talking about -- Chapter 3, The Spider's Web.
What part of the LMoP adventure am I missing that would motivate the PCs in that adventure to do the jobs in chapter 3 for free?