Getting on the A8Edit
If you want to go towards Stuttgart this spot is perfect. There is an Esso gas station at the B10/B28 just before the Ikea intersection. It takes about 10 minutes to get on from there.
If you get dropped off at the trainstation you can get there easily by taking the crossover left of it, going right and left again into Bleichstraße. At the end of it you will find the gas station.
If you want to go towards Nürnberg it is more time consuming, but within an hour you should get away (one hour for one girl hitchhiking on her own). Otherwise try getting to the Spot in Neu-Ulm directly.
If you want to go south you can try the Gas station on the other side of the road. It is not perfect, but also works.
Getting on the A7Edit
If you want to travel on the A7 try to start directly in Neu-Ulm.