Being tied up is obviously the whole experience to bondage. Some people like the feeling of helplessness, where the dominant can do anything they wish to the person bound.
This re-enforces the sub's actions at escapism and being at their masters/ mistresses mercy. Japanese bondage is the most elaborate form and it can take many years to become accomplished at this. However simple knots and ties can be sufficient in most cases.
There is being hog-tied where your arms and legs are being pulled "into" the body. Also you have spreader bars and bondage furniture ie: crosses etc. where the limbs are being pulled "away" from the body. It just depends on what you require.
Sex slave
Being bound and gagged is most popular and a ball-gag can be bought from most outlets for that extra kinky twist to your ideas. On such occasions remember your submissive will not be able to give a safe word to their dominant so a hand signal or other facial gesture will be needed.
Rope bondage, can be separated into many niche areas. However breast torture or breast bondage is very popular. This enhances sexual pleasure and the tightening of ropes around the female figure and specifically the breast area should help in each others role-play - where required naturaly.
As explained earlier a tied up submissive should never have ropes tied directly around the neck and then the limbs as this could cause strangulation. Utilise a leather collar and make full use of the metal rings for the rope to be pulled through.