Here's my opinions as a guy who shops the internet alot. BTW I don't own any internet retail shops, and this post turned out to be alot longer than I had planned.

Things that keep me coming back
1- Fair price (notice I didn't say the lowest price). Item #2 is equally important, and I'm willing to pay a few bucks more if I know #2 is there.
2- Great customer/technical sservice. If I have a question I want a good usefull answer, and not some snide, condesending, or incomplete answer.
3- Easy Hassle free return/repair policey- I very seldom return something I buy, but if I get it and it's broke, not going to work, or I just changed my mind, I want to be able to return it for my money, and not in store credit, or be charged a restocking fee. I understand some items can't be returned (ammo, openned software for example). If I need something repaired I want it done fast and with few hassles.
4- Fair shipping, I love free shipping, but don't mind paying for shipping, if I'm only charged the shipping cost. I really hate paying a fixed shipping price that I know is two or three times higher than the actual shipping chargers incurred by the vendor. Normally I'll go somewhere else, even if in the end I'd end up paying about the same.
5-Easy to navigate web site, with prices. If I have to call or email to get a price I'll find some where else to go. Plus if it takes me more than a few minutes to get zeroed in on what I'm looking for, I'll find a new site.
6- Easy to remember URL.

The following things don't influence me much.
1- Coupons, or discounts on future purchanses. I shop the web a lot, and return to sites a lot, but not with enough frequency to make these incentives very meaningful. In your case I'm not going to be purchasing scopes very often.
2- Freebies that come with the product. Unless the freebie is something I would be buying anyway I just don't care. For example, scope rings with a scope, but often I find myself upgrading scopes and don't need the rings.

How to get me to your site:
1-Word of mouth is great, but that's hard on the internet. You might hit boards like this one offer up good, reliable information, and include a link to your site - but don't make your posts be plugs for you site.
2-Work on your meta tags, and submit your site to search engines. If I type in optics or scopes on google, you want you site to be listed in the top ten. Make sure your site description is good, so when your site does come up, guys like me can see what you have to offer.
3-Ebay - If I had a internet store, I would regurally offer items up for bid on ebay. This has several advantages, first your auction turns into an ad for you that goes to a very large but specific audiance. Second, as you sell items and build up a good number of positive feedbacks, others will have more confidence in you, and will be more willing to bid. If you do, do ebay make sure you take credit cards. Signup with Paypal if you have to. Think about it, if you sitting at your computer shopping, convenience is a big thing. The last thing I want to do is go get a money order, and mail it. Wait 3-10 days for everything to clear, when I could just type in the CC number and be done with it.
4-Pay for ads on popular related sites. If you sell scopes an ad on HuntingBBS might pay for you.
5-Swap links with other revalent sites.

Sorry for the long post - I hope some of this helps, I'm not a internet retailer, or guroo but I do shop it a lot, and know what I like.

Good luck
Rkensparc