John McTernan: Three pieces of advice to the man with the best job in Scotland …

It is a great privilege to be Scotland's man in the Cabinet. But plan carefully. You have one of the smallest teams of any Secretary of State – just over 50 staff. And a budget of 6m a year compared to the 35bn annual spend of the Scottish Government. Use every member to the best of their abilities. You will find civil servants provide Rolls Royce support. Your new best friend is your diary secretary. Make sure everyone – from your family to No 10 – knows that if it's not in your diary, it's not happening. So many people will want to see you – and you need a filter. Your press team will be your Praetorian Guard. Listen to them.

And this is the key. A successful SoS steers, they don't row. Work out what you want to do, where you want to go – but don't do it yourself. You will have three main areas to focus on.

Firstly, you have one of the greatest responsibilities in the Cabinet – the future of the UK. A Cameron Premiership has been eagerly anticipated by the First Minister. He will now return to his illegal referendum with renewed vigour in the belief that independence can be sold as an escape hatch from the "cuts". This is the message he failed to sell in the election campaign. But the FM hopes there will be an emotional spasm in Scotland at the prospect of a Tory government imposing cuts. You, along with other Lib Dem ministers, will be dependent on how the first Lib/Con Budget comes out.

But remember, the SG have never looked seriously at asset sales, merging back office functions or getting value for money in public spending. And the SG are at odds with public opinion. Scottish families and businesses have had to tighten their belts. They see no reason government shouldn't go on a diet. You must make the case for reducing the deficit – it's in the national interest, will deliver economic stability and is what the voters wanted – while passporting the responsibility for unpopular decisions onto the SG.

Secondly, the biggest policy challenge in your in-tray is implementing the response to Calman. Strengthening the Scottish Parliament is an agreed objective between your coalition and broader civil society. But it must be soon – and it must draw a sharp dividing line with the nationalists. You need a consensus that isolates your opponents.

Finally, you need a presentational strategy. You need to be seen. To be ubiquitous. If it's Scottish, do it. From drinking Irn-Bru to welcoming our boys home from Afghanistan. Achievement is 25 per cent perspiration, 75 per cent promotion.

And one final note of caution, of course you are proud to be the first Liberal SoS for Scotland in nearly a century – but keep it for your conference speeches. You need to put country before party at every stage, and to be seen to do that.

John McTernan is a political strategist. He was a political secretary to Tony Blair and a special adviser to Scottish secretary Jim Murphy.