if you like; if you prefer; if it's okay
Used to offer an alternative or make a suggestion in a considerate way. Often softens a proposal.
If you like, I can do it for you.
If you prefer, shall we wait a little longer?
if ... doesn't suit you; if you don't like ...
Used in the pattern ...が何なら to suggest an alternative when the first option is not acceptable. The preceding clause states the potentially unsuitable thing.
If this color doesn't suit you, we can change it to another one.
what's more; furthermore; in fact
Colloquial. Adds an additional point, often to strengthen a statement or offer an even better option. Similar to 'in fact' or 'even'.
He can speak English. What's more, he can also speak French.
if so; if that's the case; then
Colloquial. Used to respond to a situation or statement by suggesting a course of action. Similar to 'in that case' or 'then'.
"I'm free tomorrow." "If that's the case, why don't we go see a movie?"