It should have been sprayed with roundup last September. Tilling it and planting in the spring is going to give you SEVERE weed problems.
If you want to do it right, till in mid/late april, wait 4 weeks, spray with round-up, wait 6 to 8 week (even till again) spray with round up. Mid august spray again and plant oat/buckwheat/turnip mix. MAYBE and its a big MAYBE also seed a clover mix. If its been an overgrown field you are going to have a HUGE wed seed load. You may need to repeat the above a 2nd year then also seed you clover mix. Then you will have a weed free plot. Lime ASAP