There are 3 ways to go with this: the fastest but very expensive by performing long chains of synths (5, 6 steps) or the cheapest but very time consuming short chains (by performing just few steps). And the third way is any chain between both extremes.
If you really arent hurting by money, you can pick a chain that uses HQ2 and HQ3 spheres. Check BG table of skillchains to draw some paths.
Only real problem you will have is finding enough spheres to perform the skillchain. Asura has loads of sphere bazaars. Just stay there and keep buying pieces for your chain. Then use it and either wait a restock or try another chain with spheres available or farm some