if you're playing direct, I'd get a good DI, but the definition of "good" would depend on your budget. A Tech21 NYC BDDI is the classic choice. If you're doing worship music, that might be all you need, but I would add a tuner. I would recommend a Sonic Research Turbo Tuner. A few bucks more, but fast, stable tuning even on the B string. After that the options become nearly infinite as it would really depend on what songs you're playing, if there are any signature bass sounds in those songs, etc. I would also recommend a compressor if your sound person isn't compressing the bass. If they are, maybe a limiter to keep any nasty spikes from hitting the PA.