It Depends...
Gary:
Don't know what kind of instrument time you have in your book, so I'll be as generic as possible.
1. Every flight is an opportunity to practice. Use standard rate turns and try rolling out on a heading using just a TC and compass while counting off seconds. Remember the bank angle for a standard rate turn? How much lead you need on roll-out? Know your power settings for different descent rates at cruise and Va. Fly with precision - headings and altitude. You can be practicing and your passenger won't even know it.
2. Hand fly as much as possible. If you "need" an everyday friend, get a dog. Use your autopilot to free you up when things get busy.
3. File when traveling cross country. If you're a low instrument time pilot, being "in the system" in nice weather will make you more comfortable when the weather turns. You wouldn't want to learn to sail in a Force 5 gale, right?
4. Practice "under the hood" with a friend/safety pilot should be a regular thing. Keep setting goals for yourself - How much needle deflection will you accept on a precision approach? How much altitude variation on a non-precison?
5. Most important, get and stay comfortable with the gages. Instrument flying, like acro and formation, is a perishable skill. It's not a bad idea to go up with a good instructor every now and then an have him wring you out. That will keep you from developing bad habits and ingraining these thru repetition.
Is this all cost effective? It depends. I've seen more than a few golfers spend thousands on equipment, nothing on lessons (all the pros have swing coaches), no time on the practice range, and then wonder why they can't get their handicap under 15. Remind you of any pilots you know?
Terry, CFI
RV-9A N323TP