Asking your acquaintances for something like investment funds over email is a big no no. Would you like to get that email? How would you respond? "Asking for advice" and "I need your help"? That's not being direct or forthcoming. You're losing trust and credibility before you even start.
People generally don't like being asked for money. If you're bootstrapping and need funds from friends and family, start with family first then your closest friends and then, only then, reach out to people outside of that circle.
Your family will (or should) invest in you because they love you and believe in you. They probably won't care very much about your business plan or idea. Once they're on board, your friends will invest (likely in smaller amounts) for the same reason as your family but they'll want to know that your family is supporting you first. If they're not, it doesn't breed confidence. Lastly, acquaintances should be pitched on "what's in it for me" basis (in other words, how much money are you going to make me and how) and you should start your pitch with "my family and friends have already backed me with $X and now I need $Y to do Z".
And for the love of God, schedule a meeting over coffee. And make sure you pay. Unless you've been taken hostage and you're emailing to ask someone to wire funds for your release, don't ask for money over email. It's just rude.