Have a look in the FTP rebellion page they have a lot of advice for FTP and newer players.
This is a pretty good event for newer players doesn’t have any season 1 heroes in it. so if you do have enough gems to do a 10 pull you could end up with some pretty good 3s and 4s to pad out your roster.
If you do get lucky and pull Panther or someone else 5*, resist, the urge to level them up until you have a solid 4* roster. You will progress further with a good bunch of 4* than 1 special 5*. Levelling up a 5* could slow you down in the short term. 5* will eventually tip you over the edge in your progress but you’ll need the 4*s to do your day to day farming and quests etc to get the Mats to level the 5s… .
The Challenge Event portal is great for low-paying players to get new heroes in. But don’t pull until you have enough gems for at least a 10-pull. One at a time isn’t really worth it.
I also recommend you concentrate on the 4 stars for now until you have a solid bench. 5 stars take ages and lots of resources to max for newer players. You will gather more of those resources from the game using 4 stars for now, in preparation of moving on to the 5 stars later.
I’d go even further depending where you are with roster development. Build up the Rares to obtain the Epics, and then build those up for the eventual Legendaries.
During this time of slowing building up your roster, you should be obtaining the 4* ascension materials you’ll eventually need for the Legendaries. A good and understanding alliance will help on this front.
From my personal experience I have always had better luck in portals when making 10-pulls. Most of my good 4* and 5* heroes have come from 10-pulls as opposed to singles. As mostly f2p myself it takes a while to save up that many gems.
Mathematically it shouldn’t make a difference, every pull is independent at the stated odds. But colloquially the odds seem to even out more over a 10-pull as opposed to ten single pulls. At least in my experience … others may differ of course.
The FTP Rebellion, that Owzat linked to, is a very nice corner, come on over
Lots of nice advice given already in this thread. 10 - summons are a bit cheaper in gems, than single summons too. One of the best things I did was summoning x 30 in Valhalla. I was lucky and got three star heroes that overhealed, gave minions etc. and that really helped me along greatly in events, raids, Titans, everywhere.
Now, there might be better options available - like those portals where no Season 1 heroes are at. I´m afraid I´m not up to date with what´s the best place to summon - I haven´t even taken a look at S5 yet either. But the ongoing portal right now is free from S1 heroes as far as I am aware.
I hope you´ll have lots of fun with it, good luck ahead, and welcome