Find Me a Lodger!
What type of person and let do you want - e.g. a student, a professional, someone letting part time (i.e. a Monday - Friday lodger), and what kind of lodger can you realistically attract, given your home and its location? For example, are you close to a university? Or perhaps a hospital? Other large employers in your area (especially if you're looking for a midweek lodger)?
It might be worth approaching the university housing officer or a hospital or other large organisation's HR department, and let them know you have a room to let. What about public transport links and local amenities? Is your area very residential?
Check specialist house and flat share websites such as Spareroom.co.uk to get an idea of the quality of rooms and rental rates for your area, before placing your own ad for a flatmate (this includes a lodger or housemate). Specialist flatshare sites carefully vet adverts before they will publish them, making them safer and less vulnerable to spammers than general advertising sites. Rooms 4 Key Workers will advertise your room initially for free, only charging an advertising fee when you find a lodger or tenant through their site. They also only advertise to public employees such as police officers, teachers and civil servants who have already undergone a disclosure and barring (DBS) check (or the older CRB check that DBS has recently replaced) and must be of reasonable character.
You can also use social media to advertise, which can also provide the advantage of giving you a general impression of the person first BUT beware of being lulled into thinking you know people from this alone - you must still carry out due diligence - interview and thorough tenant and background checks - before making a definite offer.
Wording the ad and photos
Looking on room to let sites such as Spareroom, the ads that are the most appealing not only include plenty of detail about the property being let, including plenty of good photos of the room itself and other rooms in the property, and a little information about the location, but go into detail about the people who already live there, their lifestyle, habits and routine - for example, they like a quiet life mostly, but like to relax with friends around on weekends; what they do for a living, and how this impacts on them at home - for example, they work long hours, but want their space when they're at home; how they want their lodger/housemate to use the house and fit in with them etc. For more detail about this, including how to take good photos, see Advertising Tips for Live In Landlords on Spareroom. You might also want to consider going to one of Spareroom's speed flatmating events in London or Manchester, but remember, this can't replace a proper interview or exchange of information and definitely doesn't replace screening and agreeing house rules.
Also, match the style of the wording to the kind of person you want; don't make the ad sound very friendly and personal if you'd just like the lodger or housemate to stick mostly to their room and just use the rest of the house when you're not around, but on the other hand if you're happy to have someone who will integrate with your household, you might make the ad more informal and include more personal detail about yourself and others the lodger will share with (e.g. "I'm an avid Man U fan, while my existing lodger, Darren, likes films and travel. We will consider Man City fans, but only if they concede Man U's the better team!!"). Having said that, though, it's probably not best practice to word your ad to state something along the lines of, "Lodger Wanted, Must Wear Walrus Costume..."
A note of caution - don't assume that if you're acquainted with or even friends with someone, that you know all there is to know about them - talk through your mutual expectations and agree rules with them just as you would with a stranger - if you don't, believe me, there's a lot more to be lost!
However you go about finding potential lodgers, don't forget to use common sense and consider your safety - don't give personal details in ads (set up an email address for replies) and have someone else there or meet in public when you meet them first time. For further safety advice, including some comprehensive tips from the Suzy Lamplugh Trust, visit Spareroom.