For me, the best source of seed investor introductions (relevant firm and getting to the partner directly) was from other founders. And the best source of getting introductions to founders was, ironically, from seed investors.

Even having a small network on day 1 is enough to bootstrap but you need to consciously grow. And yes it will feel slow at the beginning.

The easiest way is to reach out to entrepreneurs that have raised before and see if they are willing to be an advisor in exchange for equity in your company. If you have something they believe in, they won't hesitate to introduce you to investors they know in exchange for equity in your company.

If you go through the advisor agreement at https://fi.co/fast you can get a sense of how much equity you should give up.

If your next questions is how to find these entrepreneurs, go to LinkedIn, TechCrunch and so forth and cold email people you find and ask them if they would interested in being an advisor.

start with angels, look in online communities for your niche, it’s like dating