Can I install custom ROM on Android mobile having low internal memory? I want to install the latest custom ROM like Lollipop but my mobile has low internal memory, about 150MB.
Will that be a problem during the installation of the new custom ROM?
I have already rooted my phone and I'm worried that my mobile could get bricked.
No it will not effect

Just place the ROM in sdcard and flash it through custom recovery by following given steps properly and flash the ROM which is developed for your device  otherwise you will end up having bricked your phone.

If your device have low RAM it may become laggy.

Share the link of ROM that you want to flash and detail of your phone.May be we can help you little better