Bribing as you described it, lol is also an example of relationship building. If you do it only gain it may help you a lot because most people don't do stuff like that.
The real key is to understand how powerful relationships are in life and treat people in a certain way that you display this.
For instance you may go and get service somewhere and they do a superb job. Let them know, let there managers know and reward them if you wish (now that is a good job) just like Jimmy prescribes by going the extra mile. (yes a pizza to share amongst the crew will do)
It's a gesture that says you guys are great and I appreciate that. Use this mentality (not necessarily the act of physically give a pie but the mindset of showing your appreciation) in life to build relationships with every one you do business with especially if it is an ongoing relationship.
It will make you stand out among customers and treated more like a friend. Of course this usually mean quicker or better service.
Remember your attitude matters in life. If can hold you back or catapult you forward.