First thing to do is set a budget. It seems obvious, but you should have a maximum amount you're willing to spend. Hired music entertainment can start anywhere from free if it's a family friend, to thousands of pounds for full bands or an array of entertainment. Then there are celebrity acts such as chart toppers that you can get, if you can get them and if you're willing to pay the price. Secondly, make sure the venue will allow entertainment, and whether they have they use a 'sound limiter' as sound limiters impede the general sound and atmosphere of some acts and performers. Some venues have to appease the neighbours by setting a maximum level of music. Also, check with the venue that there is easy access to the performance area and that heavy loading equipment can be brought into the venue from a nearby parking area as close to the venue as possible.