I am planning to invest 5000usd every month into crypto for next 3 years . So please suggest me which coins to buy how much. I am not a risky trader or investor i want to play a safe game as much as possible
Well the thing is, you must understand that there is no such thing as an "expert" in the network, even that person you think is, can also put a foot wrong every now and then and make a mistake, so why i said all that is to encourage you to do your own research as it is very important, more often than not when you ask questions such as this, people give you the ideas of coins they are hodling, they do so to hype/pump it, but in the long run it could turn out not to be the coin that suits you.
Having said that, since you say you're not a risky investor (though any sort of crypto investment carries a certain percentage of risk), i think Bitcoin could be the perfect choice for you, but mind you that you must have to be patient and wait for the long term if you finally decide to go with Bitcoin, it is in no way a get rich quick scheme, but definitely in the long run you will accrue good ROI. Another thing you must do is to select a suitable strategy, going by your OP you have decided to go with the DCA which isn't bad at all, especially for a newcomer.