Questions on Margin

Hi Pat. Merry Christmas to you and happy new year. I have two questions regarding margin. 1) When I go on margin, do I buy stocks until my broker tells me I do not have buying power left or do you need to pay attention to something else like current excess liquidity ? 2) When on margin and I follow your proposed stock selling rules (tail bars, undercut of 8/21 EMA), can there be a chance I can get a margin call or can this only happen if I don't cut my losses at some point ? Do I need to pay attention to something else like current excess liquidity ? Appreciate your feedback. Thanks, TJ