If u have 10k in qualfd acct but managed at a full brokerage what is the best way to $ cost avg and what funds

What I would do is transfer the account to a solid mutual fund company such as Vanguard, T Rowe Price, or Fidelity and remove myself from the high cost brokerage. Each of these companies not only has a full range of more or less solid mutual funds to choose from, they also offer brokerage services for stocks, etfs, bonds, etc. Their brokerage commissions vary somewhat from one to the other, but in all cases they will be cheaper than the full service broker. One of my favorite funds is T Rowe Price Capital Appreciation Fund, a real long term very solid performer. At Vanguard their World Stock Fund is a fine long term performer. At Fidelity they have several good performing funds but none that particularly shouts out at you "buy me". I do however have one of their funds.

I am not certain there is a particularly best way of dollar cost averaging. The question perhaps becomes more of how often should purchases be made--monthly, quarterly, annually. I believe each of these companies will allow you to buy $50 or so a month of a particular fund and even automatically withdraw the money from your bank account.

One of the problems with $ cost avg is the psychological impact. It becomes very frightening pumping money into a fund that continues going down month after month after month. And a lot of them have been known to do so. It is not nearly so frightening pumping money into one that goes up month after month.