Yes, it's a good thing! Let me give you some tips from years of signing experience:
1. Get both the name of your initial contact and the name of the weekend manager (who is normally not the person you're working with.)
2. Visit the store you'll be going to on a day when the weekend manager is on duty. Introduce yourself and smile a lot. Buy something to show that not only do they support you, as an author, you support THEM too.
3. Find out where, in that particular store, they normally host authors. Don't presume it'll be right at the front of the store. Often it's in the back or in a special "events" section. Don't be discouraged if it's nearly in the furnace room. Instead, use it to your advantage! Plan to make nice, printed signs directing readers to your location, and ASK if it's okay to post them on the day. Every store has different rules, so accept whatever they say and punt.
4. Find out if they're ordering the books or if you're providing them. If you're providing, find out from the event manager if you can get barcode labels printed by the store's system to put on books you sell. Trust me that the register workers won't know how to cope if a book is handed to them and it's not in their system!
5. Get an announcement in the city's newspapers weekend events calendar. This is normally free. If you're a local author to the store location, see if the paper will do a small write-up or review.
6. Call the store the morning before the signing and ASK if they'll post the signing on the sign board outside. Don't presume they'll just do it by themselves.
7. Don't presume the table will be set up or suitable for the signing. While most stores are on the ball, things can and do fall through the cracks. Plan to bring along a simple tablecloth, which tends to look more professional than a bare table.
8. Even if the store is ordering, bring a dozen or more along, "just in case." Maybe lots of sales, or none arrived despite being ordered, etc. Now, not every store will let you bring your own copies. But if it's their screw up, sometimes they'll bend to keep people happy.
9. Bring your "A" game on the day. Lots of smiles and "Hello"s, and a willingness to talk to people. Know that a lot of people will walk by without making eye contact. That's a defensive technique to avoid buying things not on their list. That's okay. Really. Sometimes they'll buy the moment you walk out of the store. Weird but true. Offer to sign the leftover stock. Stores generally like to have autographed books in the store, and you get some free placement, as the store will often showcase the signed books in a "quick gifts" section or in the "new fiction" area with a prominent autographed sticker.
10. Thank everyone in the store you come into contact with. Be polite and know you're a complication to their day. But if you're nice and you sell a few books, they'll invite you back.
Good luck & enjoy. Signings can be quiet or busy. You just never know. But they're definitely worth the effort.