This is a question I get asked a lot. How do you determine who to tip and who not to tip? I often get asked if the DJ should be tipped, but what it comes down to is that everyone you hire for your wedding is providing you with a "service". We know that 95% of the time tip is included for catering and servers, so why is their "service" more important than others? There is make-up, hair, DJ, photographer, planner, videographer and officiant and so on. That is a lot of people and a lot of extra money if you start tipping everyone! So how do you decide?
There are a few ways to look at it. A great place to start is if the vendor works for a bigger company. Sometimes, if you hire a DJ (for example) for a company that has several DJ's that they contract and send out on jobs, then it is customary to ask during your initial meeting if a tip is expected for the DJ. This is because the DJ who works the event is not taking the entire profit, but is being paid a sum for performing on behalf of the company (who receives the other portion). The company will typically say it is up to you, in which case you can judge them on their performance and handle accordingly. You can either give them the tip at the end of the night or give it to your planner to hand out. If their performance was just so-so, then don't feel you have to tip. Tipping is for exceptional service and should not feel obligatory if you received sub-par service.
If another vendor (your photographer or planner for example) works for themselves, then you may not feel as comfortable being so forward as to ask if a tip is expected. In any case, they will likely say no. They are charging you already for what they feel the cost of their services is and typically will not expect a tip. The same rule applies, however, for service. If they go above and beyond and stay longer or take extra pics that aren't contracted or are helpful beyond your expectations, then it is at your discretion to give them something extra at the end of the night.
It is a fair rule of thumb to use these two guidelines as you thank your vendors at the end of the night. Same goes for hair and make-up. If you are in a salon, you will typically tip. If they come to you and are doing a bunch of girls' make-up at $100 pp, then you can certainly ask (when contracting) if tip is included (since they get all the profit) or if it is expected on top. It is far better to have all questions asked up front and feel awkward for a brief moment than to find out after the fact that they were expecting a tip all along and you thought it was taken care of!