I am new to dslr photography, i started with Canon 550d DSLR camera with efs 18-135mm kit. I am interested in macro and portrait photography. Can anyone tell me for which kind of purposes i can use my current lens and which lenses i need to buy for macro and portait photography.
If you are on the budget, you can try some m42 prime lens for Portrait photography. You can get some of the decent m42 lens for 20 to 50 USD over Ebay (Pentacon, Helios, Zeiss Tessar etc). Some of them cost much more as they are very sharp lens. Make sure that the focal length is from 50mm to 135 mm as they will give some great results for Portrait. Also, make sure that the aperture is 1.8 to 2.8.
Macro Photography: You can get the Canon macro lens with AF (expensive), old macro lens (cheap but Manual focus), Macro filter (cheap but image degradation), extension tubes (AF is little expensive but manual is cheap) or reverse ring to mount the kit lens in reverse to decrease focal length and make it a macro lens to some extend (very cheap but depth of field is very shallow)