I'm planning to upgrade to nikon D610?

I hve a 50mm f/1.8mm and a old 18-55 f/3.5 kit lens from my D3000, which ;ens sud i go for next?
i usually do candid wedding photography, product n a bit of street photography.
budget is a concern.coz i don't want to invest too much as off now. As photography is just a hobby/part time occupation
please recoment some good lens and added accessories

A D610 is a substantial upgrade, and pretty expensive.

I'd start with more glass. Look for an 85mm prime.

24-70 f2.8 or 70-200 f2.8

Upgrading to a full frame dSLR is quite a leap.

Your 18-55 mm and 50 mm lens will work with the D610, however, you may want to buy more glass for now and learn how to use the lenses on your fine D3000.

There's NOTHING you can't do with your D3000. The D610 has a larger sensor, but unless you are planning on making billboard size prints or shoot all your images for printing posters that are 2 x 3 feet, the D3000 is enough camera for now.

Spending the money that is burning a hole in your pocket on a third or fourth lens makes more sense.

I had ten lenses before I added a full frame camera to my kit.