consider yourself as investor and customer then look at their product, will you invest into it? then if you are a customer, will you buy their product? If both you answer yes then you should join their bounty
This is good advice. Participating in bounty means that you support the project and advocate it. So you should join bounties of projects that you consider investing in.
I invested to Neufund and I truly think the project stands out from others. That's why I also participate in their bounty, to promote the project so it will be more successful, which is good for them and also for me as investor. And I will get some extra tokens as reward.
If you don't have the money to invest in any ICO, then look for projects that already raised sufficient amount of money. This means that projects are serious and they have enough support to succeed. If the project has enough investors, the price will not drop when hitting the exchange. Some projects offer huge bounty rewards but they don't sell enough tokens and this means that price will fall because most bounty participants dump tokens as soon as they get listed on exchange.
There's one more thing you need to check before you decide for a bounty campaign - is payment fixed (for example 100 tokens per week) or you get stakes (for example 2 stakes for Jr Member, 3 stakes for Member...). If it is fixed, then check the ICO price for one token and calculate how much are those 100 tokens worth.
If bounty pays you in stakes, in this case it's more tricky to calculate and predict how much you will get. First you need to check what is total number of tokens reserved for bounty, let's say 100 000. Then you need to know what percentage of that is reserved for your bounty campaign, for example for signature campaign, let's say 30%, meaning 30 000 tokens. Lastly you need to check spreadsheet how many people already joined signature campaign and predict how many people will join till end of campaign. Let's say there are already 100 people and you expect another 100 to join after you because it's the middle of campaign. So you calculate how many tokens is each person getting. 30 000 / 200 = 150 tokens per person for the whole campaign (not per week!)
This is not very accurate calculation, because some people get more/less tokens depending on their rank, I also didn't take into account that some people participated for the whole campaing and some people only for last week or two.
One more thing, some bounties promise high payments, but then they pay less than expected. This is the case with ICOs which reserve PERCENTAGE OF SOLD TOKENS for bounty, and not fixed number of tokens. So if ICO collects small amount of investments and they don't sell all their tokens, this means that they will give only percentage of that small number of sold tokens, so they will give very small number of tokens to bounty members.