Promoting 25 unrelated affiliate programs from one website means you have multiple streams of income. The more content you have on a website that promotes an affiliate program, the better you chances of a sale.
Content is king, so overload that affiliate promoting website with content.
Banner ads are the most effective way to promote an affiliate program. Even more effective if those links are part of your own personal recommendation of the product or service. The more affiliates your program has, the better. Lower commissions but more sales might earn you a higher commission. Even better if your commission is earned every month - not only the first month.