If you want to be a good successor in crypto and you want to make a large sum I'll advice you perticipate in bounty
Once you must make a choice in between any of these options, then there are two things which carry the most significance importance. The first one is your financial status and the second one is the knowledge which you have regarding the things. I will go for trading but only when you are this much capable and that otherwise, it is better to go for participating in either signature or bounty campaign.
Financial status is not actually applicable to bounty as you can easily start that at any point in time, and the only status you need for that is the availability of resources to achieve the objective of any of those bounties and get something good from them. Personally, bounty is the easiest among all of them that the OP mentioned, and as long as you can easily familiarize yourself with the environment, picking a good project to do a bounty for will even gets easy.
From my experience i think better will be for every newbie if they start bounty firstly.Then he can do everything when he will get some rewards from bounty.Bounty is the only way where you can earn bitcoin or eth without invest.When you will get handsome amount of dollars then you can invest in an ico or trading or lending.
Bounty can only be easy for a newbie if the resources are there to pull it off. Bounty also have its own requirement, but it is the easiest and the safest to do without much risk involved except if a project fails or ends up going rogue. For bounties, you can easily make good bucks from tokens, and if you even have some special skills like writing and all, it makes things easier for you at the end of it all.