Welcome to the forum..... congrats on the certification and rezki tergolek hehehehe
Anyhow Ketam suggest getting basic gear such as Mask, Fin and dive comp first. Your own regulator are also a good idea at the moment. Wet suit should be next.
Mask and fin are very subjective and personal, you are never going to be happy with rented ones. Dive comp are vital safety equipment and they are rarely available for rental. Your own regs so that you know its usage and maintenance history. Wet suit because everybody pees in theirs hehehehe.
BCD if you have balance cash (you can rent them anywhere), DSMB is also a key equipment. Choose wisely and do not buy on impulse. Try and ask the other forumers on their views. Ketam's 1/2 cent view hehehe