I live in a country with many mozzies and at the moment we are having a large amount of people getting dengue fever due to bites.
My DH is an magnet for mozzies and have tried every lotion and potion under the sun (inc help from a Tropical hospital) the only thing that works to stop the mozzies or any other biting insects is deet, at least 50% deet.
I buy lots of Jungle Formular, spray and roll on, tropical high deet concentrate to bring back from the UK. Shop around for prices but Savers usually have to best prices (but check the size some are 90ml others 125ml cans).
Have tried Asda own brand (nope did not work) Boots, (tends to sting) Wilko (not effective) Superdrug (ok but still not as good as JF) along with many 'natural' citronella type which offered no protection at all. Have also tried local 'deet' type products, again none of which worked other than Soffel but just for a little bit of protection.
The bands, and the like, just dont work, still bite you in other places. The eating garlic/vitamin tabs, skin so soft and all those tales really dont work if your a magnet to be bitten, its not worth taking the chance.
As far as help with bites Anthisan/Afterbite/anti histamine cream are all good, but the best we have ever found is a Japanese cream called Mopiko (you cannot get it in the UK) you dont say where your going on holiday, but its worth looking at local creams as well. If your bite is really bad put cream on with an Elastoplast over to soak in (and helps to not knock to bites) a hot spoon over the bite also helps to take the sting away. The small electric zapper things do help to a point.
Yes the plug ins work, I have one in every room, but thankfully I dont have to spray each night before bed like I had to in another country I lived in with big mozzie problems. Coils I do use outside as well as lemon joss sticks.
Using lemon scented soaps and body wash are supposed to help which we do use, but always with JF after. We even had a body wash from the hospital that was like brown tar to wash with which smelt of lemon grass (citronella)
Clothing helps a lot, long sleeves, long trousers etc. but darker colours attract mozzies more than light colours. Poor DH has even been bitten through jeans on the knees, they were horrendous.
Of course what works for one may not work for another person, this is what works for us and its our routine for going out and trying everything over the years to help stop getting bitten.