there are several ways:
-Mining, but since I know nothing about it, I cannot advice on this
-Gambling: this I cannot recommend, unless you know about sports betting, but it takes experience. Of course avoid casinos at all cost, unless you are a good poker player
-Affiliation: you can subscribe to affiliate programs and earn slowly by advertising via your affiliate URL (it can be any services related to Bitcoin)
-Signature campaigns: you need to be an active member on this forum, and you will be able to apply for signature campaigns. Earning will depend on your rank (Jr Member, Member, Full Member, Sr Member etc).
To be active, you need to post 14 posts in every period of 14 days, and your activity should go like this: 14 - 28 - 42 - 56 - etc.
Monitor this page to apply for signature campaigns > https://bitcointalk.org/index.php?board=52.0
Wish you the best.
mining requires quite a lot of effort actually u need to setup devices be latest on technology,initial setup cost is high including electricity bills,so better to go for other options (as per your condition),be regular ,keep check on market and post quality posts for getting enrolled in good paying signature campaigns.