How soil is prepared before sowing will depend on many factors: what you are trying to do, slope, soil characteristics, moisture levels, compaction....
Soil Preparation options:
Working the soil pre planting may give better germination results but opens the risk of erosion if heavy rain falls before plants get established.
Rotary Hoes or Power harrows if you want to develop a fine tilthe.
Plough with narrow tynes can be used to scratch surface
Aerators do creat some disturbance and seed boxes can be fitted to the frame
Hand operated spreaders are good for small areas
Machine spreaders can be very accurate
Direct drills do not seed the soil to be disturbed but a close mow or flail mow before sowing is desirable.
Harrows and rolling
Linkage rotary hoes or power harrows can work up ground to fine tilthe very quickly
Linkage direct drill seeders or pasture seeders are good for larger areas either into worked ground or low mown grass.