No. 1: Be really careful who you pick as your co-founder. You can change your product, change your market, change which language you code in. But it's very difficult to get a divorce from a co-founder.
No. 2: Valuation isn’t everything. Getting a high valuation looks great and may be good for the ego. But when you look for people funding early-stage comapnes, look for those who can provide their time, and not just the money. In many ways, time is more important and helpful than capital.
No. 3: Reiterating No. 2. Look for investors and advisors who can commit their time to your company early on.