I expect your first buy to be in lump sum or possibly an aggressive buy in order to have a reasonable amount of bitcoin in your portfolio. Once this is done and the newbie is not satisfied with the level of his portfolio, he should embrace the DCA with all his heart and follow it. There is nothing to be careful about with DCA, as this method was carefully designed to give everyone a soft landing.
I actually disagree with you on that because aggressive investment is always not Adviseable because there is every possibility that you will get into trouble on the process, however when we talk about aggressive investment you are actually referring to investing all you have or majority of your capital on Bitcoin which is obviously not an investment advice, although we understand how potential and important investing on Bitcoin is but if you are not mindful you could end up on a tight corner.
Perhaps as a newbie who is just starting there Bitcoin journey I think the best way is not even to Lump Sum because he doesn't really no much about Bitcoin yet so the main focus should only to accumulate Bitcoin through DCA method because from there he will be free from some certain risk or missing out buying opportunities and also through the use of DCA he will now get acquainted with the ways of Bitcoin and from there he can now decide if he could utilize the Lump sum method and at the time continue with his normal DCA method.