I don’t know what your musical selections look like, but here’s how we did it (prompted by my years of experience playing piano and organ for weddings, as well as our musicians’ preference).
At the beginning of the ceremony, the varous songs used for entrances of all the players usually just follow one another. You do have to tell your musicians when to start the sequence (either to start playing altogether, or to switch from the general background music that they have been playing) – generally, you have a friend or an aunt or an usher signal the musicians from the back of the church, or make their was to the front, discretely let them know that you’re ready, and then sit down. From that point, you actually follow them. You usually have a song for the parents’ and grandparents’ to walk in and be seated, another song for the groom, groomsmen, and officiant, another song for the bridesmaids (and flower girl/ring bearer if you’re doing that), and then of course the music you are walking to. When you hear your music start (regardless of who you are) you start walking!
For songs inserted into the service, the officiant should announce the song, perhaps providing an appropriate introduction (a few words about the meaning of the song to the bride and groom, the fact that the bride’s sister is singing, etc). This should be an obvious cue for the singer to get to the microphone; the musicians should start when the singer is ready, which is generally something they can work out on their own.
For the recessional, it’s sort of obvious. The vows are over, you kiss, turn to face the audience, and the officiant announces you (May I present Mr. and Mrs. SugarSparkle!) And then the musicians start the recessional, and you walk out.
If your musicians are paying attention, it’s all pretty obvious – no need to someone to poke them and stage-whisper "Now!"
We didn’t do unity candles, sand, or any of that stuff – just a traditional service, with a couple of readings (both of which we had the pastor do) that lasted a total of about 20 minutes. Last weekend I went to a cousin’s wedding where they did a wine ceremony, a sand ceremony, a unity candle, presentation of coins, moment of silent prayer for deceased relatives… not to be unappreciative of their effort, but it went on for freakin’ ever. You friends and family (IMO) came to see you exchange vows and hear some nice stuff said about you, and then to eat and drink and dance – they’re not expecting the Cirque de Soleil. They are much more likely to get bored if they have to watch you do too many things up there than if you keep it short and sweet and cut to the reception.