Kenny Jackett is aiming to make as many as five more signings this summer.
James Bolton represents Pompey’s solitary arrival to date.
The right-back joined on a free transfer following his departure from Shrewsbury and penned a three-year deal at Fratton Park.
Meanwhile, Gary Mackay-Steven is closing in on a switch to the south coast.
Although some League One clubs have already made several signings, Jackett stressed Pompey’s recruitment team are working hard to ensure they bring in the right players who’lll bolster his side’s promotion chances next season.
And the boss has aspirations at least four fresh faces will follow Bolton through the arrival door.
Jackett told the Blues' website: ‘If we could sign five players, that would be what I would be wanting.
‘Him (Bolton) alongside four or five more signings will really help our squad.
‘There are plenty that have been talked about, but internally we have made enquiries, put bids in and made offers of wages to players who are out of contract.
‘We are actively trying to work at that to improve our squad if we can.
‘The only one we have over the line at the moment is James Bolton but we're hopeful we can work towards bringing more players in.
‘Like many people say, it's easy to bring players in but it's hard to bring the right players in and that's going to be key for us.’
Pompey return to pre-season training on Thursday, June 27.
Jackett admits ideally he’d have had the majority of his new players reporting for duty to meet with their new team-mates.
But he insisted capturing the correct players is far more important.
Jackett added: ‘We start a week on Thursday and if we can bring in the majority of the players before then we would.
‘Similarily, if we have to wait for the right players we will.
‘We have a very good nucleaus of the squad and good character.
‘This summer, we have to bring in the right people and right characters. That's really important for me and it's something we have to address.
‘Of course, new signings in time for pre-season is even better. But for right player at the right time we'll work away at it and bring them in when we can.’