In Splinterlands if you are staying still probably you are overthrown by your enemies. This is not a game for the weak souls or the lazy one, either you move with the times or you die. And one way to level up your game and keeping to be competitive is by combining cards. Why? Simply because higher levels of cards, offer better skills which can incline the odds of a battle in your favor. Strategies? There can be many, but in my opinion you should start with the goal of combining all the cards and than strategize which one to use in the battles also based on the given rules. Some cards might not be even available for you to throw in your battle, so if you picked only those cards to level up and you cannot even use them than you'll probably be throwing a weak formation to battle. Or at least that's my take on it.
From Common to Legendary
I am approaching my strategy of combining cards from leveling up first Common cards, next moving to Rare, Epic and finally Legendary. This is the least resisting way as the Common cards have a lower Glint buying cost, thus I should be able to get there faster than usual. Most of my Common cards from Rebellion edition are already at Level 8, so I just need 2 more Levels and I will have all of them maxed out.
Rebellion - Common cards
As I still had one card at Level 7, for Demo purpose I will combine it for you. The Halaran Huntress is a Common Earth Unit at Level 7 and after combining it to Level 8 I will be earning an additional 1 Life point. This should make the card last longer on the battlefield and produce more Damage.
Rebellion - Combine Common cards - Halaran Huntress
From Regular to Gold
As I've previous explained my strategy to keep the optimism at high level by combining cards faster is to go from Common to Legendary. Once I will achieve that (even if it will take me some time) I intend to move to level up Gold cards. Why? Because by simply using a Gold card and winning your battles you will get more Glint and SPS rewards. This will be much harder because Gold cards are more expensive to buy in the Glint Shop. For now I am being lucky enough to get some Gold cards from the Regular Draws. But probably there will be a time when I will move to Gold Foil draws.
Time constraints
This is a rather slower and empiric strategy to combining all the cards. The only constraint I see for it is the time until these will be available as rewards. If I find some indispensable cards on the battlefield and I didn't reach my goal, I guess I still have the chance to acquire the missing pieces on the open market. Probably that will cost me a bit, but it still represents a way to be able to maximize the level of the proffered cards.
Probably I need to hustle more and grind in order to complete this strategy. And to be truthfully I had my ups and downs in Splinterlands with days passing by and not playing it. That probably will translate in lost opportunities, but I still hope I will be able to make. If not, I will take this experience as a lesson learned and strategize better on the next edition. A rather slow strategy, but if I succeed with it that should be quite fulfilling. I will draw the line at the end and give the conclusions at that point.