If you see an app that let's you mine then you should avoid because it is a waste of time but if you are looking for a website that give free BTC and been running for so long or one of the oldest website then freebitco.in is where you should be visiting. If you really are into mining then why not buy mining rig to start mining though it will surely cost you money for the mining rig and future expenses for its maintenance. If you have money for it then why not do it but it you don't have the money for it then don't.