Hi and welcome!
I’m an old-timer, so I’m going to offer a bit of a “long view” response — E&P is a game that tends to be very much about the long haul.
In the long run… 1* and 2* heroes are ones you won’t use. I’m not saying you shouldn’t level or work on them at all, but be aware that eventually 3* heroes will be the smallest heroes you will use. (That said, as I recall, Layla was the last of my 2* I eventually got rid of.)
In the early game, one major use for gems is to summon heroes; outside of the freebie gray-token Mystic Summon portal, other portals will drop you at least 3* heroes to start working on and leveling up. If you get some 4* or even 5* heroes early, congratulations — but be aware that it might be a while before you can fully level them up and trick them out. You should spend most of your hero development time and resources (e.g. food) on 3* early on.
Level up your farms and mines as much as possible as you go. You will, short, medium, and long term always face crunches in the amount of food and/or iron.
Low level battle items can be very useful. I like to almost always have a healer hero on my teams, but even minor healing potions can be a useful backup — even as a high level player, I still find minor mana potions and regular antidotes useful. (The latter nuke ALL status ailments for a low cost, and the former can be the difference between “I get to use my Special ability that’s almost ready, and win” and “I lose” in tough fights.)
Keep an eye open for freebies — the game will have a *berjillion* different offers to sell you, but tucked in there is some free stuff (which is now marked by the little “present” icon). There are always Mystic Vision ads, which depending on your time, tolerance, and sanity, can be the single biggest source of free-to-play gems. There’s also the Daily Streak at the official website https://www.empiresandpuzzles.com/dailystreak
As you get into the game and a high enough level to be able to join an alliance, consider doing so. It’s more fun to play together, and there are some items you can get from Titans and Alliance Wars (and Alliance Quests and Monster Island and even “support your Alliance!” paid offers) that you, well, need to be in an alliance for.
I…. won’t advocate here how or whether to spend your real-world money (plenty of people spend, plenty of people are free-to-play), but I will say that you’ll want to decide whether/how much money (zero or otherwise) AND how much time you want to devote to this game. A lot of things about this game are designed to try to get you to spend always more of both! Be wary about chasing anything too hard — this is a long term game! Make sure you’re actually having fun
And
always feel free to ask questions. In game, here on these newly-reforming forums, on Discord, or other socials. It’s fun to welcome and help out new folks!