My husband and I don't go out much, but when we do, it's normally to see live music. This is my husband's great past-time outside of the Play Station and typically I'm just happy to get out of the house. I have seen some amazing bands and been to some wonderful places since I met him, through his love of live music.
Concerts are costly, on top of ticket price, there's often a service charge for buying online, travel to and from the event plus food and drink. I can't tell you how to get cheap tickets, or how to avoid paying excess booking fees, but I can tell you how to save money on your travel if you're a driver.
We're not much for drinking and typically drive to every gig we go to but parking can be expensive (around £20 at the O2 for example), it was my husband that discovered Park at my House, a website that helps you find private parking spaces around the country as an alternative to expensive parking costs. We've used it several times, parking on driveways and even in the staff car-park of a printing firm (out of hours of course) and have never had any problems. We found it particularly useful with parking for Wembley Stadium and Arena.
I'd highly recommend it to anyone attending any sort of event where the cost of parking is going to be high.
Alternatively, look at public transportation, if you're travelling from a distance, it might be cheaper to go by train, just be sure to triple-check your last trains, any works being done and have a back-up to get home (long gone are the days where my friends and I could loiter at a 24-hour coffee shop in the station waiting for the first train the next morning or walk home from North London clubs in early summer mornings).
When it comes to food and drink, events are expensive so eat a good meal before you go. Food and drink from outside the venue will often be confiscated so try not to take anything in with you as it'll probably get chucked. A large fizzy drink at the O2 is £5 but it does get hot inside, obviously alcohol will dehydrate you further so try to stick to water. It's the cheapest and most beneficial.
If you're buying merch, withdraw cash before hand, a lot of places slap on a charge for using credit or debit cards as well as at the crowded stands someone could easily see your PIN over your shoulder and nab your card. Keep your wallet/purse to the front of you (never put valuables in back pockets or bags out of your line of sight) so that you can remove and replace cash quickly when paying and know exactly where it is whilst you make your way out of the crowd.