League one gets steadily harder than league two, I am Wrexham, won the BSP, won league 2 with basically the same team but struggled in league one for 2 years and have only now just got them up, coming 2nd behind Swindon. Sign Reegans released from Premiership teams that your scouts/assisant recomends and don't be scared of selling your best players in order to make money. 2 experienced centre defenders also made a **** of a difference to my team. Pacey full backs and wingers do the trick also pacey strikers.
In pre-seasons, don't rush it. Take your time and look for players for hours, it might be boring but it makes your whole season enjoyable. I released all my youth team and brought new ones in that premiership teams released, they made brilliant back up when I got injuries and made some belting loan signings that doesn't cost any wages.
If you want anything else, let me know and I'll post a screen shot.