First and most importantly, as already suggested, take him to the veterinarian to rule out a urinary tract problem. Infections and/or crystals are not uncommon in cats (and can become life threatening in a male cat) but even more common is the "catch all" FUS... chronic urinary inflammatory problems. One of the first things cats often do to attract your attention to the fact they don't feel right, is to stop using the litter box. Diabetes and thyroid issues (also common in older cats) can also increase urination. Rule out a medical problem before you consider it to be simply behavioral.
Second most important clean it up well. Any trace of scent and the cat will keep returning. The cat can smell it even when you cannot. Get something that not only cleans, but actually breaks down the urine and removes all traces. Steam cleaning is actually the worst, as the hot water simply bakes the urine into the fibers of the furniture or carpeting. White vinegar is effective if the smell of that doesn't offend you as much.
Other suggestions are to have 1 litter box per cat plus 1 extra. So if you have only the 1 cat, have at least 2 boxes for him. Put the regular litter you use in one box and get a totally different one for the other (clay if you use clumping, etc...). When cats do have a lower UTI or FUS, they often associate their pain upon urination with the box they are using...and simply don't want to return to it. Different litter can sometimes help this issue.
Get a bigger box. Commercial litter pans are TOO SMALL for most cats. Your box should be at least 2x the length of your cat. Storage bins from a discount store with a hole cut for a doorway work great, and are usually cheaper than pet store pans. Wallpapering basins work good too if you prefer lower sides.
Put a box where he is going. The cat wants to pee there and sometimes you just have to put a box there for him to use. You can then slowly move the box a foot or two a day until it's hidden where you want it to be.
A scat-mat (or even more budget friendly- tin foil) placed on an area you don't want the cat on is effective for most. Put this up on the pool table so he doesn't jump on it. For whatever reason, most cats HATE tin foil and will not walk on it.
Feliway spray does work for some cats to calm and relax them. Some cats will pee out of the box when they are stressed.
good luck.