The setup I have now is perfect: my custom Candelas uke has a fantastic built-in pickup. You have to get the right kind of pickup, though. Mine is an L.R. Baggs, which is the best company as far as acoustic instrument pickups. And you have to have an active pickup, not a passive. Passive pickups need external amplification, so you'd need to carry around a pre-amp and maybe some pedals. Actives give you power and volume.
Fishman makes some great acoustic pickups, but they're for guitar. They're too big for an ukulele. I asked them to make me a custom uke-sized pickup, but they wouldn't do it.
An Active pickup is the only way to go. Active PUs have a battery, Passive PUs do not have a battery. So the passive is lighter and keeps a little more of the original acoustic tone, plus you never have to deal with changing batteries. But Passives have no power; they simply send a signal to the P.A.. You have to rely on the soundman for volume and tone, and he's gonna screw it up every time. The Passive signal is so weak that the soundman will have to crank the volume WAY up, and then you'll feed back like mad.
Some pickups have a volume control, others don't. You need a volume knob!
Most uke pickups have volume knobs that mount through a hole in the body of the uke, so you have to cut a hole in the instrument in order to acces the knob. Like Lanikai electrics; they have a volume and EQ built in. But they've cut a big hole in the instrument, ruining the integrity of the sound. My L.R. Baggs has a little volume dial that mounts inside the sound hole.
Another way is a piezo pickup, but that's crap. It's a stick-on pickup that sounds like crap and has no power. You'll still need a pre-amp. Plus, it will pick up all the sounds of your hand rubbing against it as you play. It's inexpensive, but it's a bad idea. Lavalier mics are a little better, depending on the brand.
I've tried lots of pre-amps and effects boxes. The only pre-amp worth anything is the L.R. Baggs Para Acoustic. Wow. It's supreme. It sounds natural, has a ton of volume and has a three-band EQ. Plus it doubles as a Direct Input box, with an XLR input built in. And another great feature is the battery compartment. When you need to change the battery, you just push a button and the battery pops out. No need to unscrew any panels. And it's indestructible. Solid steel housing.
But the easiest and best-sounding solution is the Baggs Uke Pickup. No pre-amp, just plug into the P.A. and play. It's about $200. The only place I know to get one is Candelas Guitars in Los Angeles, but he'll mail you one. Tell Tomas Delgado that I sent you!
Amplifying Your Ukulele
Pickups, Microphones and Pre-Amps VS. Raw Acoustic Sound