/ Arriving at the TGV station of Aix and then there is a convenient shuttle bus that will take you right into town. Or if you're arriving from Marseilles, for example, at the older train station, no problem, it's actually right in town, so you can easily walk from the station into the Aix town center. It's only about four blocks away along Boulevard Victor Hugo, so it's only going to take five minutes to walk from the train station into the center of Aix.
It is worthwhile stopping at the very friendly and efficient Tourist Information Office here for an excellent free map of the city and other brochures. The workers here speak English and can answer your questions, provide sightseeing tips, find accommodations and point you in the right direction. Here you can also get information about hotels, restaurants and shopping areas, and find out if there is any special entertainment scheduled during your visit.
It is always helpful to do some research, especially if you are only in town for a few hours on a day-trip as we are today, with limited time that you don't want to squander by getting lost or going the wrong way. However, while it is good to develop a plan for your visit and locate the various attractions and pedestrian lanes on a map to make sure you find the right neighborhoods, you also want to leave time for the aimless wander, follow your nose and stroll about casually, turning here or there depending on which twist looks good at the moment. The Old Town is small enough you will not get lost for long. This mystery of discovery is always a big part of the travel adventure.