With the best will in the world, painting stuff WILL involve brush strokes going awry and paint going where it definitely isn't wanted. A very common mishap is smearing colour all over the carpet when doing the skirting boards. Be sensible and put masking tape over the area where the floor meets the wall. And generally speaking, leave plenty of time to do the job. You don't want to be rushing around with rollers and paint cans around.
Not all walls are the same. Bear that in mind if you're putting a nail in to hang up that big beaming picture of your whole family. If it's a solid brick or stone wall the nail should hold, but if it's a flimsier partition, or in poor nick, the nail may come out at the merest provocation – taking chunks of wall and plaster with it. Nice work, genius.
Don't drill into things
There are few DIY nightmares that are worse than accidentally nailing or drilling into a hidden wire or water pipe. One minute you're ready to hang up a picture, the next there's water gushing out or you're getting a nasty electric shock. Be sensible, don't take chances, and use a special device that can locate cables, water and gas pipes. You can get it from any good DIY store.
Reckon your kitchen or bathroom could do with a fresh coat of paint? Not so fast – using ordinary paint in a room that's rife with humidity and condensation could mean gross outbreaks of mould in just a few months, and then you'll have to do it all over again. Better to invest in special kitchen and bathroom paint, which is pricier but will keep things looking spic and span into the future.
Flat pack frustration
Don't think putting together flat pack furniture doesn't count as DIY. It totally does, and we're horribly prone to getting it horribly wrong. Next thing you know, that giant bookcase is collapsing on your baffled head. Read the instructions PROPERLY, don't jam screws in where they don’t belong (yes, we know it's tempting to bang them in like nails sometimes). There are actual companies that specialise in coming over and putting flat pack together for you. Try one of those.
Don't be a wood wally
Let's say you have some wood furniture knocking around that's seen better days. You decide adding some new colour could really work wonders. Now stop right there and put the brush down, because if you don't SAND the stuff first, you'll likely end up with an ugly, mottled, uneven tone. Just get some sandpaper and gradually, patiently sand the objects all over, always going with the grain. It's time consuming, but totally worth it.
Do you need permission?
How's this for a proper DIY nightmare: you work your backside off cobbling together a proud new shed or office or cabin, and then some annoying man from the council comes over and tells you to tear the whole thing down. Now, it probably won't happen, but there are very specific rules about the height, area and habitability of any outside structures you might put up. So check first, just so you can sleep easy.
Keep your spirits up
There's a special syndrome with some DIY types, which makes them think they can DEFINITELY TELL when something is level, just by looking at it. The result: a slanty bookcase, which you'll then have to swearily take down and re-do. Do yourself a favour and use a good old fashioned spirit level. You probably got one in a Christmas cracker last year.
Try not to die
Putting up a wonky shelf is one thing, but getting killed or seriously maimed is probably a bigger DIY disaster, when you think about it. Believe it or not, plenty of people still die from falling off ladders every year. The rules of thumb are: don't use a ladder for long periods, make sure it's in good shape, make sure it's definitely long enough for the task at hand, and don't carry heavy stuff up and down.
You know how in cooking they say "you can always add more salt, you can't take it out"? There's a similar rule in DIY to avert disaster, and that's "measure twice, cut once". Once you saw into that bit of wood or metal, it's too late to change your mind. So make sure you measure everything properly, all of the time.