Basically I'm going to cover decision making that will be different from my guide for beginners.

My original guide can take you to level 4 no problem but at level 5, generals, bosses and minibosses is noticeably harder to kill and appear in larger quantities so things can get a little crazy.

If you grind from level 1 to 4 you should have enough currency to buy/unlock your chosen character's weapon. You might want to check out a wiki to see if it's worth it as they are not all equal strength but if there is no info out there or if your characters passive does not impress you, you probably want that bonus anyway.

The strategy is run away from minibosses as you kill soldiers to clear each stage.
The minibosses don't give you anything worth the risk of wasting your dodges dealing with their nonsense. Remember that all bosses have max distance on all their attacks.

Try to save musou and assemble if you are on a stage that has a bonus mission to guarantee you get the bonus.

For elite enemies I recommend baiting the enemies into charging their attacks before you begin your combos. Think of a bullfighter. This gives you freedom to dodge their attacks by running instead of burning your dodge which is what you would have to do if you are mid combo.
In other words, attack them in response to their attacks and not before they attack and if you bait them to start attacking faster this makes you more certain of what the actual safe places on the floor are.

Vigor - 1 (interrupt attacks charging up)
Speed- 1 (Invulnerability on dodge)
Wisdom- 2 (health regen) Invest in this the most
Charm -1 (Unlock formation buffs) Invest in this the 2nd most
Skill - Going higher than attack Actions 2 is not recommended but pick Skill over strength (shield) or elements that do not unlock any of your ally tactics.
Slay - Life draining slay is healing that adds up and basically keeping your health high is a must in level 5. There is enough emblem variety among slay heroes to make it splashable in any build.

I already went over this in my beginner guide. Difference is this time you want to be very economic on emblem choice as shops are nerfed and it's so much more likely that you will take hits/damage and so better dodging and healing are high priorities. There's also a guarantee that you run into a stage where you lose health every time you dodge and that can end your run if you haven't been investing in Wisdom, Slay and Speed.

As soon as you have 10 000 tears of blood, take the next shop you see no matter what.
Also after you beat the 3rd boss start looking for shops unless you have less than 6000 gems

One big difference between level 5 and earlier levels is R1 (right bumper) spam.
Whenever you have a summon available, get it out as soon as possible using R1 mid-combo rather than trying to complete your combo. This gets you musou, assemble and is generally better than whatever your combo was going to do and most importantly you will have more freedom to dodge by running instead of your actual dodge which should be for emergencies.

Last thing I'll cover is rerolls.
The odds of you getting 3 bad heroes to pick from is low in fact the game seems to throw you characters that complete your synergies when they are about to be complete. The purpose then of a reroll is to DIG through for the hero you WANT out of an emblem tree or golden tree.
For example if you want one of the few heroes that give tears of blood or healing then the earlier you get them the better.

Trees with emblems and golden treese have smaller pools/selections of heroes so rerolls are stronger there.
In other words, if there are 4 heroes in a tree and you reroll, you are more likely to get the hero you want than if there are 4 billion heroes.

The only other time I would use a reroll is if I've had terrible luck with my starting heroes and badly need to find something good before the first boss fight.