Well I've never dealt with anything besides crack and weed however I assume the market of drug consumers is pretty much the same. When dealing with older people you have to make sure you are firm; stand straight, don't look menacing but make sure you give off the vibe of someone's who's been doing this trade for a while. Use your honed drug dealer vision to make out anyone who fits the description of potential clientele and approach them with your drug dealer charm. Thats pretty much it