How do I get designers on board, as many may say it is my first time organizing a fashion show and they can not vouch that I will have a good show?

It is advisable to channel your efforts towards building credibility since it is your first show. Be sure that you do not compromise on excellence. You can start by reaching out to personally known designers, as they will be more likely to place their bets on you. Also ensure that you pay attention to little details, such as avoiding typos in your publicity materials, etc. Securing a decent venue can also be a plus. Offering complimentary slots/discounted rates can also encourage participation, as the risk factor is reduced. In the event that you are able to win over a reputable designer or a celebrated model, take steps to publicize this, as it can serve as a means of pulling others in.