this forum is a great resource to start with. search past entries on here, too. read and compare catalog descriptions and specs on sites like B&H Video (and even call them, they’re pretty good)and then search for reviews on Youtube. that’s what i did before buying and i am generally happy with how it worked out.
for lavs, VHF is cheaper than UHF but since it offers fewer channels you sometimes get more interference. i have a vhf set from azden though and it works fine for me. you can usedifferent mics, too, not just a lav (I plug a boom into it sometimes and a regular looking mic for those man on the street interviews and it works just fine). i’m rural, so not much interference. if you’re in a city, UHF might be more important.
