This topic can be touchy for people because there are those out there who see the good in Fiverr and there are those who see the bad in Fiverr; either way you look at things there are going to be a set of pros and a set of cons for sellers on Fiverr and the money that they can make from the different gigs that they have to offer. The concept that is what fuels Fiverr is a simple one and only good is meant by it but with that being said there are still a few flaws with the system, a few here and a few there.
To be more exact there are the issues of a high commission, there are people who are considered to be spammers, there are those who have expectations that are so high they are impossible, there is the competition from the other Fiverr sellers you are up against and there is the chance that those clients you have will either not leave any feedback at all or they will leave negative feedback that is not true and this will lower your ratings.
The price for a gig on Fiverr is five dollars but after their cut you get four dollars and then eight cents less if you withdraw it through PayPal. You can make a decent amount of money with Fiverr but you do not get it right away because it has to go through what is deemed as a clearance period which is fourteen days long. As for the people who are spammers they either create fake accounts and buy from themselves to leave fake feedback or they offer services that can't be true or work such as getting you thousands of followers on Twitter and what not.
Fiverr is a great place to go for services and for the most part you do get a lot for your money but it is easy for people to forget that they are only spending five dollars for the work and you are really only getting four dollars for it so they should not expect the results as if they paid five hundred dollars or more, their expectations should be kept accurate.
If you have an idea for a gig in mind you need to check out your competition before you make your gig, see what else there is that is similar to your idea, see what they offer and the amount of time that they are asking for to get it done in. With some gigs there are too many people doing the same thing but there are some out there that are popular and the competition is not so fierce yet.
Lastly, there are going to be those clients who choose to leave no feedback at all or they will leave feedback that is not so nice, even if it is just a miscommunication any negative review or lack of review can harm and or lower your ratings and chances of being recommended to other users. Once you have found your niche then stick with it and always deliver perfection.