A lot of people want to know copywriting and how to do it, but very few are willing to put in the sustained effort and drive to achieve it. This type of writing is not easy to do even though reading a world class sales letter looks easy to write. All pros in sports tell you it is solid execution of the fundamentals that are so important to winning; same goes for copywriting.
Understand that the core of all great and effective copywriting is honesty. When you have clients, eventually you will find those who want you to cross the line in some way. The prospects going through your copy trust you to give them a viable solution that is worth spending on. If you cheat them out of their hard earned money then your copywriting career will most definitely take a hike in a short while. Even people in regular niches have seen a lot of sales letters online, and they have become sensitive to hype and things that smell fishy.
The online reader is vastly different from most offline readers, and any good course will talk about that in detail. How you present your copy, or rather how you write it for any niche will depend on who is in that niche audience. The simple reason is you need to know how to talk to them, know what matters to them and how to use their language.
Cutting and pasting copy from your offline channels is definitely not the solution because ultimately the way offline world operates is different from the online world. So try and avoid making this mistake as it goes against the basic rule of copywriting, which is to be creative and original.
If you look around the net, you can locate some sales copy that are famous and obviously very successful, and then you can study them in great detail. It doesn't matter how good you think you are, you should always be open to learn from the best. Have a willingness to work, learn and then promote yourself, and that will carry you far if you can take the heat. The thing about copywriting is it is entirely up to you; become great and stay average, good or mediocre is all up to you. Not everybody is cut out to be a copywriter because it naturally lends itself to those with certain characteristics.
Once you start discovering copywriting principles, then you will begin to really see the depth and scope of what is involved. There is too much and too many writing devices to ever need all of them in any one piece of copy. Just keep in mind that your copywriting will only improve when you consistently put in action and keep up with the practice, without which there's absolutely no way you can make progress as a copywriter that creates masterpieces.