I can't comment much on his conduct before the Spanish Civil War. However, as the overall general in charge of the Nationalists in that conflict his approach was to slowly grind down the Republican forces rather than to go for a quick victory. For instance, he chose to relieve the Alcázar in Toledo rather than pushing on to Madrid very early in the war. It was a symbolic victory, but strategically useless as far as winning the war.

However, Franco had no interest in winning the war quickly. He considered a rapid victory to actually be dangerous. He wanted to "secure" areas that he conquered, meaning to win the conflict between right and left in brutal fashion by suppressing some leftists, imprisoning others, and killing a great many. Merely having been a part of the elected Republican government was often a death sentence regardless of one's conduct before the conflict began or after it commenced. Union members, journalists, communists, socialists, anarchists, and others were targeted. The numbers are still somewhat disputed, but Paul Preston's figure of 200,000 are at minimum roughly accurate (I believe they include the continued killings from the end of the war in 1939 that lasted until 1945) This wasn't an accident either. It was planned, as was Franco's campaign to slowly win the Spanish Civil War rather than go for a masterstroke like seizing Madrid immediately after getting the Army of Africa to the mainland in 1936.

Time and time again Franco deliberately chose to grind through an offensive of his own choosing, slowly pacify an area in his rear, then move onwards. He would also repeatedly refuse to cede any territory to Republican offensives. Instead of attacking their flanks or taking advantage of the numerical advantage that the Nationalists had to attack somewhere else (where the Republicans had to be weak), Franco would choose to counterattack directly into the Republican advance. He also promised Nationalist offensives in support of his allies who lent troops to his cause, but then failed to deliver. This was the case at the Battle of Guadalajara, where Italian troops were left to fight Republican reinforcements that could have been tied up by the promised and absent Nationalist offensive.

Franco was deliberately not a dynamic strategist in order to fulfill his war aim of winning the fight between right and left in a way that was meant to be final. The best source on Franco's approach is Preston. He touches upon the idea in The Spanish Civil War, but goes into depth in The Spanish Holocaust. For the actual military conduct of Franco's forces Beevor's Battle for Spain is superior, but he doesn't get into the why as much as he does the how.

As always, followup questions from OP and others are encouraged.