For starters, you must understand that there are always high and low ends of giving an acceptable tip. You just can’t choose to be extra generous on a particular day and start breaking the bank just so that everyone likes you for rewarding them. Therefore, know your capability and your bank balance and give a tip which will suit not only the other person but also your own pocket.
Always make sure you understand the kind of service you are receiving. Each and every service has its own personal percentage. However, there are a few services which are given at a flat rate. For instance, a car washer or a furniture mover is always going to get tipped at a flat rate. Once you get done after your car has been washed, you would give the person $2 - $ 5. On the other hand, a furniture mover might receive more since ($10 - $50) since he is putting in more effort. As for the percentage, hairstylists and waiters usually receive a tip in the range of 15 to 20 percent. As for fast foods where you get a pizza delivered, you should tip them at least 10 percent of the total amount. However, it is advised that you do not pay less than $2.
Mostly it comes down to your own judgement. There is basically no difference between 15 or 20 percent when the only change that occurs is of a single dollar. This one dollar is going to help you improve your relationships with that particular person for future references. When it comes to people who you have to pay at the end of the month or a week, you are not supposed to tip them every day. You should pay them at the end of the month.
Make sure you are discreet. For instance, if you are paying for a household service, paying them in an envelope is a good idea.