Most of the advice I get online is x$ per hour. But that's not really helping me. I have a full-time job to do and it's difficult for me to allocate hours per day/week. I will freelance as per my will in a given deadline.
However how do I quote a price on the project? To make a web application with 5 features say?
Instead, you should bill based on the value to the client, in terms of increased revenue or decreased costs. For example, in 2007 I built an online appointment scheduler with real-time availability for a high end Beverly Hills hair salon. It took about 20 hours of work total. If I billed say $50 an hour I'd have $1000. Instead I sold them on the fact that they didn't need to hire a full time receptionist at $24k per year, and I was able to charge them $6000 for the project. They are still using this system today.
You aren't just competing with their existing solution, you are competing with other developers that they are likely collecting quotes from.
IMO your ability to charge them $6000 was based more on them not knowing exactly how much work went into the project and not the value it saved the company.
This was also addressed in the ebook, and charging significantly more than your competitors is a strategy in itself. If they go with a competitor based on price, this is not a client I want (low end market ironically is more demanding than the high end). I get fewer clients, but still make more money than the cheaper guy (e.g. sell 1000 Bentleys or 20,000 Fords).
1. Wild guess.
2. Figure out how much the customer is willing to spend.
3. Figure out how much you need to make.
4. Get estimate from a cheaper freelancer on UpWork, X 2.
5. Through experience understand the customer, the job, and your own productivity.
The questions you are asking demonstrate that you aren't ready for professional freelancing, so any of the first four models I listed will work for you.
Since customers are usually interested in both budget and schedule, freelancing "as per my will in a given deadline" should make you even more attractive.
Don't like snarky, sarcastic replies? Then take yourself seriously and don't insult professional freelancers. With just a little bit of effort you can read hundreds of articles about freelancing, project estimation, scheduling, client relationships, requirements gathering, planning, and execution. Actually learning these things and doing them right takes practice. A professional freelancer is not just an unemployed developer or someone with extra time on their hands.
My freelancing business is taking over projects that failed or stalled because of bad estimates, bad schedules, bad planning, bad execution, and poor communication. So welcome to the "freelancing world," you're keeping me in business.
I have several relevant articles on my own website about freelancing. You can find plenty of good advice (and even more bad advice) online.