Don’t try to raise funds which are required for next 5 years, in short don’t raise all funds in one go, you need to go step by step. Be clear as for what funds are required and where they will take the company and what all is to be achieved. This also helps you in getting good valuations when you go step by step. It also ensures that you get good funds for the dilution of equity that you do when you go step by step.
When you go for first round of funding the equity you dilute will be higher when compared to funds received as your valuations will be low, but when you go for second round the lesser equity you dilute the more funds will come in as your valuation will be entirely double of what it was when you went for first round.
It’s just the same way you cannot eat everything in one go, you need to eat as and when you are hungry the same principal applies here.