It is hard to built interest without at least one other person there to play a game and get people to stop by to have a look. Nice terrain has been a big draw for tournaments in North America and Australia. NOVA Open, particular, has gotten a good reputation for terrain which builds public interest. It can be expensive to get it made but I think a few nice pieces might be worth it. Some Rohan houses or Hobbit holes might work for their recognizably.

When I started getting into organizing games I went to someone for advise and the most important thing to building up a community was showing that there were people who wanted to play. People who were interested will not invest if they don't think there are other plays. You wont be able to just host a demo and have people pop out of the woodwork to play. You are going to have to be at store every week, at the same time, for two hours and do your best to bring people over with nicely painted models and terrain. Then you have to pitch the game to them and tell them how to get into it without sinking a bunch of money.

It is also important to have a store with some financial incentive to let you come in and use a table. If they don't sell Middle Earth models they are not going to have a good reason to put up with you. If they do, on the other hand, then they will want to keep you around to try and make some sales. When I started I went to a GW store about the time the shift to ME:SBG happened. The store did not do much in ME sales but they were going to have a promotional stand anyway so I was free advertising.

Gondor at War is coming out soon. I recommend that you put together a themed demo game between Gondor and Mordor. Maybe even play one of the scenarios if there is a small one in the book. Run something soon after the book comes out and then be down there regularly after at times the store is busy with foot traffic. A weekend afternoon perhaps. If you have any non-gaming friends ask one or two to come by and have a demo as a favor to make it look like their is interest to people who are on the fence. That is my suggestion.