Pick a venue near your fan base to make it easy for them to attend. Well-known concert halls and clubs help boost the credibility of a music event. The venue should have enough room and the right acoustics for the event. A concert will require a larger space for the band and the singer to be set apart from the audience. An album release party lends itself to a smaller venue and a more intimate setting. Visit the venue beforehand to test out the acoustics in the room. A room that produces a lot of echo will need a sound system set differently than one that does not naturally produce a lot of echo.
Rent a sound system and hire someone that knows how to use it. Don't try to figure it out by yourself. This is one area you'll want to outsource. It doesn't matter how well the band or singer performs if the audience can't hear well due to a loud screeching microphone. Some venues will have a sound system you can rent, others will not. Find local system rental businesses and compare their daily rates. Ask the rental company or the venue you selected if they have recommendations for a sound technician.
Arrange for enough seating depending on your confirmed guest list. People are more likely to stick around if they have somewhere to sit and rest their feet during an event. If you are appealing to an older crowd, seating will be expected for comfort purposes. Younger groups, such as those in their late teens and early twenties may not mind standing around listening to music. Chairs should not be placed closed to the sound system. This can be damaging to the audience's eardrums and uncomfortable for listeners. Chairs should be placed in a way that allows of people to walk freely about the room during intermissions.