I agree with all the above.
You'll find that, by today's standards, the earlier Monogram kits are quite basic in comparison, with many modern kits having more parts in the cockpit, for example, than an entire Monogram kit !
That said, many of their well-detailed kits are still being made, either under the Revell label, or under the original Monogram label.
The detail, and therefore, to an extent, the complexity of modern kits will surprise you, after so many years away from the hobby, with parts included in kits never dreamed of before. Add to that the vast array of resin, metal and photo-etched 'add on' detail parts, which just weren't around in the 1970's, and it's possible for even a novice modeller to produce now, what would have been a competition winner back then.
Some of the main manufacturers have been mentioned above, and in 1/48th scale there is now a huge selection of kits and types, where back in the 1970's these could be counted on the fingers of two hands. Have a look at some of the larger, on-line suppliers, to get an idea of what's what, and then, once you've decided more or less what you want to do, by all means ask advice, here on the forum, about particular kits.
And as mentioned, have a look at some of the reviews, tutorials and builds on this forum - there's a world of experience here, and all are willing to help.