Okay, you're not confident about asking a SD for money because you keep seeing advice against telling him about your financial troubles. I will be among the first to admit that flat out asking a SD for money is anything but easy. You have to remember that when you ask for nothing that is exactly what you'll get. I learned that lesson the hard way. There is a difference between discussing your needs, expectations, etc., and whining about your bills. It's all in the approach.
With men you meet through a sugar daddy dating site, it's a question of who takes charge first. Do not wait to talk about what you expect from them. They signed up knowing exactly what kind of website they were on. Your expectations should be a topic that is discussed very early in your relationship. If you have a brief first meeting and there is no time to bring it up then (and you should bring it up), talk to him about it before your second encounter. If you don't, you will have given up control. All you have to say to get the conversation going is, "we need to talk about what each of us expects from this." You don't have to ask for much. If you see him 3-4 times a month, $ 200 every time you get together is a reasonable place to start. For an out-of-town sugar daddy you see once a month, aim for $ 400-500. In either case, you can get him to increase his contributions a little at a time.
Now then, if the man in question is someone you met "on the street," he may not even know that he is a sugar daddy. This approach may be a bit sly, but try to get something from him every time you see him. At first, maybe you want to "go out with your girlfriends". Next time, perhaps your "car needs some work." Make sure he isn't a whiz mechanic if you go for that one (unless your car actually needs work and you don't mind him doing it). He will come to anticipate your needs and will begin to freely give you money on a regular basis.
With either type of sugar daddy, you can work your way into him paying your car payment, rent or mortgage. You can also convince him to pay for you to go back to school or to help you start a business. The key is to get over being hesitant about letting him know what you need. Very few of the sugar daddies I've known were shy when it came to what the y wanted.
Let's assume you've been regularly seeing a sugar daddy who showers you with gifts, but what you really need is money to pay your bills. After you've been seeing a sugar daddy for awhile it is going to be more difficult to broach the topic than with someone new. In any case, you still need to test the waters. Sit down with him and have a frank, but gentle, conversation. You may want to start off by saying, "I really enjoy spending time with you. I love that you buy me x, y, z. But I could really use some help with my rent / mortgage / car payment." Judge his reaction to that request and choose your next move.
If he freaks out, he is either more into having a girlfriend than a sugar baby or he feels like he would be buying your "services" if he gives you cash. You may be able to wear him down over time, but don't count on it. I don't suggest that you end the relationship, but keep looking and meeting other potential sugar daddies. Eventually, you will find a man who doesn't freak out when you bring up the subject of an allowance. Instead he'll be more than happy to help you.