So far I'm having an easy time of it all.
Some things to remember on your first play through if your unfamilair with how things are working.
1. Spells, weapons, etc remember what is working. On your second play through if there is one you'll know more about everything and can find easier ways to do things. At times it's easier to go through the slog of a first play through partly then restart as a new character.
2. Never use your heavy spells for simple fights, or minions. Instead focus the big guys, just pummel the hell out of them with your heavy damage abilities, then mop up the minions after that.
3. look for spell synergy have a warlock. Use true strike, then witchbolt on same target, need more drop hex on that target to. Have a wizard grease and fire spell. Fighter give them a couple haste potions, and nearly all your healing potions. Pop haste on first round, dash to a target and unload. Same with action surges.
4. Use height to gain advantage so your missing less with spells, and sneak attack from ranged until your tanks (most armored and healthiest characters generally Fighters) can get into positon. Then begin to run in with rogue, and sneak attack with a double team. or just stay back and sneak attack from ranged.
5. Have an escape for your wizards, misty step is great. Can't hit someone magic missile the hell out of them. It never misses though damage isn't as high as other spells, still your doing damage.
6. Armor up before fights with spells they stay on until you long rest for the most part. Beef up your characters AC with cleric buffs before fights, or their stats.
7. Debuff the enemies heavy hitters. If it's a melee character using a big 2h weapon hit them with a strength hex, if they have alot of hp hit them with a con hex.
8. look, listen, learn. Look around to see what you see. Narrow choke points, interactables lovingly placed to plummet on enemies heads, plants that entangle, etc. Listen oh not much here. Learn from everything you do. save before battle to test it out if it's your first time, see who's hitting the hardest, who your missing the most etc.
9. Deny, deny, deny! Deny the number advantage of your enemies with sleep spells, or halt spells, throwables that force them to roll a save, like grease bombs etc. Use these and if a couple people end up falling blast the grease with fire!
10. Look at every spell you have on level up, stop and think how you'd use them, how they work together.
11. never use health pots/spells to heal outside of combat. Use the food you find to heal up, short rest, or even long rest. Conserve your big heals, health potions for and only for battle. Don't use healing word unless you can't get to the downed person within 3 turns. Cure wounds heals far more on average. Which brings up this one. Your cleric is your life, protect them. (unless your wizard has Larianed healing spells.) even then wizard won't heal as much as a Life Cleric, and he should be pumping out damage, or denying movement. Also his heals are (in my opinion haven't tried it out and wont) going to be weaker then your clerics. (this part is an assumption and not tried by myself)
12. Last of all..... uggg... cheese them... just straight up fumundah cheese them. If they're close to an edge give them a bonus action shove, to help them down. I mean everyone needs some help even if they don't understand they do. To close to your Wizard give them a shove, and a face full of magic before running away.