There are ways to advertise for free online, some sites provide you with good amount of space to advertise for free.
Next, Yellow Pages and some ad mags also provide free advertising service. Plan and schedule them first.
You can save some amount of money in this,
but many a times free advertising may not be that effective, hence you need to go for the only alternative left. Yes,advertising by paying.
Next, you need to estimate the possible revenue or the outcome you may gain without advertising and after advertising. If the difference is large then go for that type of advertising whether giving ads in newspapers or magazines or through television etc.
Now you have estimated that you will gain profit through advertisement, you are going ahead to arrange further. Estimate the cost incurring for the media people, the venue,special arrangements like snacks, etc.
Plan your budget accordingly to call how many audience or spectators should be there. If the cost goes too high, cut the number to only few VIP's.
Once you decide how much is the budget, adjust and allocate this to individual tasks.
Proper planning is absolutely essential for any advertisement to become successful.